video: seps525: Add seps525 SPI driver

Add support for the WiseChip Semiconductor Inc. (UG-6028GDEBF02) display
using the SEPS525 (Syncoam) LCD Controller. Syncoam Seps525 PM-Oled is RGB
160x128 display. This driver has been tested through zynq-spi driver.

ZynqMP> load mmc 1 100000 rainbow.bmp
61562 bytes read in 20 ms (2.9 MiB/s)
ZynqMP> bmp info 100000
Image size    : 160 x 128
Bits per pixel: 24
Compression   : 0
ZynqMP> bmp display 100000
ZynqMP> setenv stdout vidconsole

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>