drm/gma500: Make SGX MMU driver actually do something

Old MMU code never wrote PDs or PTEs to any registers. Now we do, and
that's a good start.

Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>

diff --cc drivers/gpu/drm/gma500/mmu.c
Simple merge

diff --cc drivers/gpu/drm/gma500/psb_drv.c
Simple merge

diff --cc drivers/gpu/drm/gma500/psb_drv.h
Simple merge