media: v4l docs: move some cross-reference identifiers

Sphinx doesn't allow placing those cross-reference identifies
everywhere. Misplacing them cause those warnings:

  Documentation/userspace-api/media/v4l/hist-v4l2.rst:818: WARNING: undefined label: control-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/hist-v4l2.rst:853: WARNING: undefined label: reserved-formats (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst:47: WARNING: undefined label: reserved-formats (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/subdev-formats.rst:39: WARNING: undefined label: v4l2-subdev-mbus-code-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/subdev-formats.rst:53: WARNING: undefined label: v4l2-subdev-mbus-code-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/subdev-formats.rst:67: WARNING: undefined label: v4l2-subdev-mbus-code-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/subdev-formats.rst:83: WARNING: undefined label: v4l2-subdev-mbus-code-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/subdev-formats.rst:97: WARNING: undefined label: v4l2-subdev-mbus-code-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/subdev-formats.rst:140: WARNING: undefined label: v4l2-subdev-mbus-code-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-decoder-cmd.rst:75: WARNING: undefined label: decoder-cmds (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-dqevent.rst:234: WARNING: undefined label: control-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-g-dv-timings.rst:156: WARNING: undefined label: dv-bt-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst:41: WARNING: undefined label: ctrl-class (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst:246: WARNING: undefined label: ctrl-class (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst:269: WARNING: undefined label: ctrl-class (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-g-modulator.rst:100: WARNING: undefined label: modulator-txsubchans (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-g-tuner.rst:119: WARNING: undefined label: tuner-rxsubchans (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst:167: WARNING: undefined label: control-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst:245: WARNING: undefined label: control-flags (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst:396: WARNING: undefined label: ctrl-class (if the link has no caption the label must precede a section header)
  Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst:73: WARNING: undefined label: v4l2-subdev-mbus-code-flags (if the link has no caption the label must precede a section header)
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Documentation/userspace-api/media/v4l/pixfmt-reserved.rst

@@ -19,12 +19,12 @@ please make a proposal on the linux-media mailing list.
 
 .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|
 
-.. _reserved-formats:
-
 .. raw:: latex
 
     \small
 
+.. _reserved-formats:
+
 .. flat-table:: Reserved Image Formats
     :header-rows:  1
     :stub-columns: 0

Documentation/userspace-api/media/v4l/vidioc-decoder-cmd.rst

@@ -129,12 +129,12 @@ introduced in Linux 3.3. They are, however, mandatory for stateful mem2mem decod
       -
 
 
-.. _decoder-cmds:
-
 .. tabularcolumns:: |p{5.6cm}|p{0.6cm}|p{11.1cm}|
 
 .. cssclass:: longtable
 
+.. _decoder-cmds:
+
 .. flat-table:: Decoder Commands
     :header-rows:  0
     :stub-columns: 0

Documentation/userspace-api/media/v4l/vidioc-g-dv-timings.rst

@@ -240,12 +240,12 @@ EPERM
 	There are no horizontal syncs/porches at all in this format.
 	Total blanking timings must be set in hsync or vsync fields only.
 
-_dv-bt-flags:
-
 .. tabularcolumns:: |p{7.7cm}|p{9.8cm}|
 
 .. cssclass:: longtable
 
+.. _dv-bt-flags:
+
 .. flat-table:: DV BT Timing flags
     :header-rows:  0
     :stub-columns: 0

Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst

@@ -342,12 +342,12 @@ still cause this situation.
 
 	Ignored if ``count`` equals zero.
 
-.. _ctrl-class:
-
 .. tabularcolumns:: |p{7.3cm}|p{2.0cm}|p{8.0cm}|
 
 .. cssclass:: longtable
 
+.. _ctrl-class:
+
 .. flat-table:: Control classes
     :header-rows:  0
     :stub-columns: 0

Documentation/userspace-api/media/v4l/vidioc-g-modulator.rst

@@ -119,12 +119,12 @@ To change the radio frequency the
 
 	Drivers and applications must set the array to zero.
 
-.. _modulator-txsubchans:
-
 .. tabularcolumns:: |p{6.0cm}|p{2.0cm}|p{9.3cm}|
 
 .. cssclass:: longtable
 
+.. _modulator-txsubchans:
+
 .. flat-table:: Modulator Audio Transmission Flags
     :header-rows:  0
     :stub-columns: 0

Documentation/userspace-api/media/v4l/vidioc-g-tuner.rst

@@ -296,10 +296,10 @@ To change the radio frequency the
 	instead of 62.5 kHz.
 
 
-.. _tuner-rxsubchans:
-
 .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|
 
+.. _tuner-rxsubchans:
+
 .. flat-table:: Tuner Audio Reception Flags
     :header-rows:  0
     :stub-columns: 0

Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst

@@ -494,12 +494,12 @@ See also the examples in :ref:`control`.
 
    \normalsize
 
-.. _control-flags:
-
 .. tabularcolumns:: |p{7.3cm}|p{1.8cm}|p{8.2cm}|
 
 .. cssclass:: longtable
 
+.. _control-flags:
+
 .. flat-table:: Control Flags
     :header-rows:  0
     :stub-columns: 0

Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst

@@ -79,14 +79,14 @@ information about the try formats.
 
 
 
-.. _v4l2-subdev-mbus-code-flags:
-
 .. raw:: latex
 
    \footnotesize
 
 .. tabularcolumns:: |p{8.8cm}|p{2.2cm}|p{6.3cm}|
 
+.. _v4l2-subdev-mbus-code-flags:
+
 .. flat-table:: Subdev Media Bus Code Enumerate Flags
     :header-rows:  0
     :stub-columns: 0