[media] mt9v032: Fix binning configuration

The sensor can scale the image down using binning by 1, 2 or 4 in both
directions. Update size enumeration and ratio and binning factor
computation accordingly.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>