V4L/DVB (11304): v4l2: remove v4l2_subdev_command calls where they are no longer needed.

Several i2c drivers still used v4l2_subdev_command, even though they were
converted to v4l2_subdev. Remove those unused .command callbacks.

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