drm/radeon: Use direct mapping for fast fb access on RS780/RS880 (v2)

v2: fix trailing whitespace

Signed-off-by: Samuel Li <samuel.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/radeon_asic.c b/drivers/gpu/drm/radeon/radeon_asic.c
index 06b8c19..a2802b47 100644
--- a/drivers/gpu/drm/radeon/radeon_asic.c
+++ b/drivers/gpu/drm/radeon/radeon_asic.c
@@ -122,6 +122,10 @@
 		rdev->mc_rreg = &rs600_mc_rreg;
 		rdev->mc_wreg = &rs600_mc_wreg;
 	}
+	if (rdev->family == CHIP_RS780 || rdev->family == CHIP_RS880) {
+		rdev->mc_rreg = &rs780_mc_rreg;
+		rdev->mc_wreg = &rs780_mc_wreg;
+	}
 	if (rdev->family >= CHIP_R600) {
 		rdev->pciep_rreg = &r600_pciep_rreg;
 		rdev->pciep_wreg = &r600_pciep_wreg;