[media] docs-rst: media: Switch documentation to V4L2 fwnode API

Instead of including the V4L2 OF header in ReST documentation, use the
V4L2 fwnode header instead.

Signed-off-by: Sakari Ailus <[e-mail]>
Reviewed-by: Laurent Pinchart <[e-mail]>
Tested-by: Hans Verkuil <[e-mail]>
Tested-by: Philipp Zabel <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/media/kapi/v4l2-core.rst

···
     v4l2-mc
     v4l2-mediabus
     v4l2-mem2mem
-    v4l2-of
+    v4l2-fwnode
     v4l2-rect
     v4l2-tuner
     v4l2-common

Documentation/media/kapi/v4l2-fwnode.rst

···
+V4L2 fwnode kAPI
+^^^^^^^^^^^^^^^^
+.. kernel-doc:: include/media/v4l2-fwnode.h

Documentation/media/kapi/v4l2-of.rst

···
-V4L2 Open Firmware kAPI
-^^^^^^^^^^^^^^^^^^^^^^^
-.. kernel-doc:: include/media/v4l2-of.h