V4L/DVB (13644): v4l: add new v4l2-subdev sensor operations, use g_skip_top_lines in soc-camera

Introduce new v4l2-subdev sensor operations, move .enum_framesizes() and
.enum_frameintervals() methods to it, add a new .g_skip_top_lines() method
and switch soc-camera to use it instead of .y_skip_top soc_camera_device
member, which can now be removed.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Reviewed-by: Sergio Aguirre <saaguirre@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>