The purpose of this patch is to avoid zeroing the lower 12 reserved bits
of surface base address registers (framebuffer & sprite).  There are bits
in that range that may occasionally be set by BIOS or by other components.
Signed-off-by: NArmin Reese <armin.c.reese@intel.com>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>