media: imx274: V4l2 driver for Sony imx274 CMOS sensor

The imx274 is a Sony CMOS image sensor that has 1/2.5 image size.
It supports up to 3840x2160 (4K) 60fps, 1080p 120fps. The interface
is 4-lane MIPI CSI-2 running at 1.44Gbps each.

This driver has been tested on Xilinx ZCU102 platform with a Leopard
LI-IMX274MIPI-FMC camera board.

Support for the following features:
-Resolutions: 3840x2160, 1920x1080, 1280x720
-Frame rate: 3840x2160 : 5 – 60fps
            1920x1080 : 5 – 120fps
            1280x720 : 5 – 120fps
-Exposure time: 16 – (frame interval) micro-seconds
-Gain: 1x - 180x
-VFLIP: enable/disabledrivers/media/i2c/imx274.c
-Test pattern: 12 test patterns

Signed-off-by: Leon Luo <leonl@leopardimaging.com>
Tested-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>