media: ov5647: change defaults to better match raw camera applications.

Specifically:

* AWB is now off by default.

* AEC/AGC is also off by default.

* The default mode is changed to the 10-bit 2x2 binned mode.

AWB and AEC/AGC can be re-enabled using the usual V4L2 controls. The
original 8-bit mode will be respected if an application requests the
8-bit format.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Signed-off-by: Naushir Patuck <naush@raspberrypi.com>