Remove soc_camera framework dependencies from tw9910 sensor driver.
- Handle clock and gpios
- Register async subdevice
- Remove soc_camera specific g/s_mbus_config operations
- Add kernel doc to driver interface header file
- Adjust build system

This commit does not remove the original soc_camera based driver as long
as other platforms depends on soc_camera-based CEU driver.
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>