V4L/DVB (12706): gspca - sn9c20x: disable exposure/gain controls for MT9M111 sensors.

Using the MT9M111's IFP to handle exposure/gain gives better results.

Signed-off-by: Brian Johnson <brijohn@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>