media: imx214: Add imx214 camera sensor driver

Add a V4L2 sub-device driver for the Sony IMX214 image sensor.
This is a camera sensor using the I2C bus for control and the
CSI-2 bus for data.

Tested on a DB820c alike board with Intrinsyc Open-Q 13MP camera.

[Sakari Ailus: squash exposure time max limit patch]

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.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+samsung@kernel.org>