drm/vc4: Add missing __iomem annotation to hw_dlist.

This is the pointer to the HVS device's memory where we stored the
contents of *dlist.
Signed-off-by: NEric Anholt <eric@anholt.net>

drivers/gpu/drm/vc4/vc4_plane.c

@@ -39,7 +39,7 @@ struct vc4_plane_state {
 	/* Offset where the plane's dlist was last stored in the
 	 * hardware at vc4_crtc_atomic_flush() time.
 	 */
-	u32 *hw_dlist;
+	u32 __iomem *hw_dlist;
 };
 
 static inline struct vc4_plane_state *