sm501: implement acceleration features

This patch provides the acceleration entry points for the SM501
framebuffer driver.

This patch provides the sync, copyarea and fillrect entry points, using
the SM501's 2D acceleration engine to perform the operations in-chip
rather than across the bus.

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Signed-off-by: Simtec Linux Team <linux@simtec.co.uk>
Signed-off-by: Vincent Sanders <vince@simtec.co.uk>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>