V4L/DVB (10724): saa7110: convert to v4l2_subdev.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
[mchehab@redhat.com: fix merge conflict with removal of v4l2_ctrl_query_fill_std()]
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>