radeon: add radeon prime vmap support.

This is the same as the nouveau code pretty much.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 492654f..2e24022 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -346,6 +346,9 @@
 	/* Constant after initialization */
 	struct radeon_device		*rdev;
 	struct drm_gem_object		gem_base;
+
+	struct ttm_bo_kmap_obj dma_buf_vmap;
+	int vmapping_count;
 };
 #define gem_to_radeon_bo(gobj) container_of((gobj), struct radeon_bo, gem_base)