[media] v4l-dv-timings.h: Add to device-drivers DocBook

There are already markups for documentation at v4l-dv-timings.h,
however, they're not properly formatted.

Convert them to the right format and add this file to
the device-drivers DocBook.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>

Documentation/DocBook/device-drivers.tmpl

@@ -233,8 +233,8 @@ X!Isound/sound_firmware.c
 !Idrivers/media/dvb-core/dvb_ringbuffer.h
 !Iinclude/media/v4l2-ctrls.h
 !Iinclude/media/v4l2-event.h
+!Iinclude/media/v4l2-dv-timings.h
 <!-- FIXME: Removed for now due to document generation inconsistency
-X!Iinclude/media/v4l2-dv-timings.h
 X!Iinclude/media/v4l2-mediabus.h
 X!Iinclude/media/videobuf2-memops.h
 X!Iinclude/media/videobuf2-core.h