media: docs: media: v4l: uapi: Fix field type for SUBDEV_ENUM_FRAME_SIZE

The documentation for the VIDIOC_SUBDEV_ENUM_FRAME_SIZE ioctl
incorrectly refers to struct v4l2_subdev_mbus_code_enum as the
parameter. Fix this.

[Sakari Ailus: Rebased on top of Dorota's documentation patch]
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst

@@ -39,7 +39,7 @@ Supported formats can be retrieved with the
 ioctl.
 
 The enumerations are defined by the driver, and indexed using the ``index`` field
-of the struct :c:type:`v4l2_subdev_mbus_code_enum`.
+of the struct :c:type:`v4l2_subdev_frame_size_enum`.
 Each pair of ``pad`` and ``code`` correspond to a separate enumeration.
 Each enumeration starts with the ``index`` of 0, and
 the lowest invalid index marks the end of the enumeration.