This should improve performance by avoiding uncached reads by the CPU (the
point of having a status page), and may improve stability.  This patch only
affects G33, GM45 and G45 chips as those are the only ones using GTT-based
HWS mappings.
Signed-off-by: NKeith Packard <keithp@keithp.com>
Signed-off-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NDave Airlie <airlied@redhat.com>