ARM: 6643/1: ep93xx: add framebuffer support to edb93xx boards

The ep9307, ep9312, and ep9315 variants of the ep93xx processor include
the raster engine needed for framebuffer support.

This allows the EDB93xx boards with those processors to use the
framebuffer driver.

Tested on an EDB9307A with the following kernel parameters:
	video=640x480-16@60
	video=1024x768-16@60

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>