[media] soc-camera: Unregister v4l2 clock in the OF bind error path

The v4l2 clock registered in soc_of_bind() must be unregistered if an
error occurs and makes the function fail.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>