drm/udl: add cache flags definitions for udl_gem_object

By default set udl_gem_object as cacheable, but set WC flag when attaching
dmabuf. In udl_gem_mmap() update cache attributes based on the flags, similar
to exynos_drm_gem_mmap().

Signed-off-by: Haixia Shi <hshi@chromium.org>
Reviewed-by: Sonny Rao <sonnyrao@chromium.org>
Reviewed-by: Olof Johansson <olofj@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h
index c7490a2..3082780 100644
--- a/drivers/gpu/drm/udl/udl_drv.h
+++ b/drivers/gpu/drm/udl/udl_drv.h
@@ -25,6 +25,9 @@
 #define DRIVER_MINOR		0
 #define DRIVER_PATCHLEVEL	1
 
+#define UDL_BO_CACHEABLE		(1 << 0)
+#define UDL_BO_WC		(1 << 1)
+
 struct udl_device;
 
 struct urb_node {
@@ -69,6 +72,7 @@
 	struct page **pages;
 	void *vmapping;
 	struct sg_table *sg;
+	unsigned int flags;
 };
 
 #define to_udl_bo(x) container_of(x, struct udl_gem_object, base)