drm/radeon/kms: use correct BUS_CNTL reg on rs600

BUS_CNTL is at 0x30 on rs600, not 0x4c.
Signed-off-by: NAlex Deucher <alexdeucher@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/rs600.c

@@ -426,7 +426,7 @@ int rs600_gart_init(struct radeon_device *rdev)
 	return radeon_gart_table_vram_alloc(rdev);
 }
 
-int rs600_gart_enable(struct radeon_device *rdev)
+static int rs600_gart_enable(struct radeon_device *rdev)
 {
 	u32 tmp;
 	int r, i;
@@ -440,8 +440,8 @@ int rs600_gart_enable(struct radeon_device *rdev)
 		return r;
 	radeon_gart_restore(rdev);
 	/* Enable bus master */
-	tmp = RREG32(R_00004C_BUS_CNTL) & C_00004C_BUS_MASTER_DIS;
-	WREG32(R_00004C_BUS_CNTL, tmp);
+	tmp = RREG32(RADEON_BUS_CNTL) & ~RS600_BUS_MASTER_DIS;
+	WREG32(RADEON_BUS_CNTL, tmp);
 	/* FIXME: setup default page */
 	WREG32_MC(R_000100_MC_PT0_CNTL,
 		  (S_000100_EFFECTIVE_L2_CACHE_SIZE(6) |