video: add OpenCores VGA/LCD framebuffer driver

This adds support for the VGA/LCD core available from OpenCores:
http://opencores.org/project,vga_lcd



The driver have been tested together with both OpenRISC and
ARM (socfpga) processors.

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>