media: ov8856: Add support for OV8856 sensor

This patch adds driver for Omnivision's ov8856 sensor,
the driver supports following features:

- manual exposure/gain(analog and digital) control support
- two link frequencies
- VBLANK/HBLANK support
- test pattern support
- media controller support
- runtime PM support
- enable Vsync signal output
- supported resolutions
  + 3280x2464 at 30FPS
  + 1640x1232 at 30FPS

Signed-off-by: Ben Kao <ben.kao@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>