media: i2c: ov9282: Support more than 1 mode.

The driver currently has multiple assumptions that there is
only one supported mode.

Convert supported_mode to an array, and fix up all references
to correctly look at that array.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-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>