video: clps711x: Add new Cirrus Logic CLPS711X framebuffer driver

This adds support for the framebuffer available in the Cirrus
Logic CLPS711X CPUs.
FB features:
- 1-2-4 bits per pixel.
- Programmable panel size to a maximum of 1024x256 at 4 bps.
- Relocatible Frame Buffer (SRAM or SDRAM).
- Programmable refresh rates.
- 16 gray scale values.
This new driver is designed to usage with devicetree only.
The driver have been tested with custom board equipped
Cirrus Logic EP7312.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>