FROMLIST: rockchip/rga: v4l2 m2m support

FROMLIST: rockchip/rga: v4l2 m2m support

Rockchip RGA is a separate 2D raster graphic acceleration unit. It
accelerates 2D graphics operations, such as point/line drawing, image
scaling, rotation, BitBLT, alpha blending and image blur/sharpness

The drvier is mostly based on s5p-g2d v4l2 m2m driver
And supports various operations from the rendering pipeline.
 - copy
 - fast solid color fill
 - rotation
 - flip
 - alpha blending

The code in rga-hw.c is used to configure regs accroding to operations
The code in rga-buf.c is used to create (1-Level)mmu table for RGA
The tables is stored in a list, and be removed when buffer is cleanup
(am form https://patchwork.linuxtv.org/patch/42846/)

Change-Id: I3ddd885beb2388be2ef23fe75806719d1fda8695
Signed-off-by: Jacob Chen <jacob-chen@iotwrt.com>
Signed-off-by: Jacob Chen <jacob2.chen@rock-chips.com>