[media] v4l: Don't compile v4l2-int-device unless really needed

Add a configuration option for v4l2-int-device so it is only compiled when
necessary, which is only by omap24xxcam and tcm825x drivers.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>