media: ar0521: Set maximum resolution to 2592x1944

Change the largest visibile resolution to 2592x1944, which corresponds
to the active pixel array area size. Take into account the horizontal
and vertical limits when programming the visible sizes to skip
dummy/inactive pixels.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>