Make sure busmastering gets disabled on module unload.

shared-core/radeon_cp.c

@@ -1719,6 +1719,11 @@ static int radeon_do_cleanup_cp(drm_device_t * dev)
 			dev_priv->gart_info.addr = 0;
 		}
 	}
+
+	/* Disable busmastering */
+	RADEON_WRITE(RADEON_BUS_CNTL, RADEON_READ(RADEON_BUS_CNTL) |
+		RADEON_BUS_MASTER_DIS);
+
 	/* only clear to the start of flags */
 	memset(dev_priv, 0, offsetof(drm_radeon_private_t, flags));