V4L/DVB (11426): gspca - m5602: Don't touch hflip/vflip register on Read/Modify/Write

Touching the hflip/vflip register while doing the read/modify/write corrupts the image. Just read from the sensor ctrl cache instead and all is good.

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