V4L/DVB (9967): cs5345: convert to v4l2_subdev and fix broken s_ctrl.

Converted to v4l2_subdev. While doing that I also discovered a stray 'break'
that broke the S_CTRL handling. Fixed that as well.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>