V4L/DVB (12540): v4l: simplify v4l2_i2c_new_subdev and friends

Rewrite v4l2_i2c_new_subdev as a simplified version of v4l2_i2c_new_subdev_cfg
and remove v4l2_i2c_new_probed_subdev and v4l2_i2c_new_probed_subdev_addr.

This simplifies this API substantially.

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