[media] v4l2-subdev: add start/end messages for log_status

Add the start and end messages for log_status when called from a
subdev device node.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>