[media] v4l: Remove module_name argument to the v4l2_i2c_new_subdev* functions

The argument isn't used anymore by the functions, remove it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>