Staging: fbtft: add ssd1325 controller support

That patch adds support for SSD1325 controller.
That is 4bpp grayscale OLED display controller present in several
displays eq: Winstar WEX012864

Signed-off-by: Alexey Mednyy <swexru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>