V4L/DVB (12173): mt9v011: properly calculate image resolution registers

Instead of working with a table of precalculated values, fill them with
the proper values. Also, adds format functions that allow changing the
resolution, by cropping the image to the center of the sensor.

While here, move the sensor version check to the probe routine, to
indicate to the caller if the sensor is not supported by this driver.

Also, fixes a stupid bug where we're using &buffer[] instead of
buffer[].

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>