[media] v4l: Unify selection targets across V4L2 and V4L2 subdev interfaces

Change the users of V4L2_SUBDEV_SEL_TGT_* targets to use V4L2_SEL_TGT_*
instead. The common definitions are moved to a new header file,
include/linux/v4l2-common.h.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>