[media] soc-camera: Make clock_start and clock_stop operations optional
[media] soc-camera: Make clock_start and clock_stop operations optional

Instead of forcing drivers to implement empty clock operations, make
them optional.

v4l2 clock registration in the soc-camera core should probably be
conditionned on the availability of those operations, but careful
review and/or testing of all drivers would be needed, so that should be
a separate step.

Signed-off-by: Laurent Pinchart <3ded2f39a78f0d7044839546f95841842b4d7c96@ideasonboard.com>
Signed-off-by: Guennadi Liakhovetski <50875182aae23d69ca7738697596f18a14e926fc@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <ad86ba2154032c9f55743a190faa2459a9d61d42@osg.samsung.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs