docs: driver-api: add clk documentation

The clk.rst is already in ReST format. So, move it to the
driver-api guide, where it belongs.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/00-INDEX

@@ -82,8 +82,6 @@ cgroup-v1/
 	- cgroups v1 features, including cpusets and memory controller.
 cgroup-v2.txt
 	- cgroups v2 features, including cpusets and memory controller.
-clk.txt
-	- info on the common clock framework
 cma/
 	- Continuous Memory Area (CMA) debugfs interface.
 conf.py

Documentation/admin-guide/kernel-parameters.txt

@@ -518,7 +518,7 @@
 			those clocks in any way. This parameter is useful for
 			debug and development, but should not be needed on a
 			platform with proper driver support.  For more
-			information, see Documentation/clk.txt.
+			information, see Documentation/driver-api/clk.rst.
 
 	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
 			[Deprecated]

Documentation/driver-api/index.rst

@@ -17,6 +17,7 @@ available subsections can be seen below.
    basics
    infrastructure
    pm/index
+   clk
    device-io
    device_connection
    dma-buf