drm/i915/display: in skl_surf_address check for dpt-vma

touch dpt_vma->node only if dpt-vma is not NULL
Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231116150225.204233-2-juhapekka.heikkila@gmail.com

drivers/gpu/drm/i915/display/skl_universal_plane.c

@@ -1006,7 +1006,8 @@ static u32 skl_surf_address(const struct intel_plane_state *plane_state,
 		 * The DPT object contains only one vma, so the VMA's offset
 		 * within the DPT is always 0.
 		 */
-		drm_WARN_ON(&i915->drm, plane_state->dpt_vma->node.start);
+		drm_WARN_ON(&i915->drm, plane_state->dpt_vma &&
+			    plane_state->dpt_vma->node.start);
 		drm_WARN_ON(&i915->drm, offset & 0x1fffff);
 		return offset >> 9;
 	} else {