[media] v4l2-subdev: fix broken subdev control enumeration

The v4l2_subdev_* functions are meant for older V4L2 drivers that do not use
the control framework yet. These functions should not be used by subdev_do_ioctl.

Most of those backwards compatibility functions are just stubs, but commit
87a0c94c actually changed the behavior of
v4l2_subdev_queryctrl, so calling that one from subdev_do_ioctl broke the
control enumeration in subdev nodes.

The fix is simply not to use those compatibility functions in v4l2-subdev.c.

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