V4L/DVB (11419): gspca - m5602-ov9650: Don't read exposure data from COM1.

ov9650: Reading the COM1 register corrupts the image.
Decrease the granularity of the exposure and limit its upper range
as setting such high values doesn't have any effect on the image.

Signed-off-by: Erik Andr?n <erik.andren@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>