drm/i915/display: Use intel_bo_to_drm_bo instead of obj->base

Xe and i915 objects have differing implementation. Use intel_bo_to_drm_bo
instead of obj->base as xe_bo doesn't have base pointer.
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231012072158.4115795-3-jouni.hogander@intel.com

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

@@ -1930,10 +1930,10 @@ static int intel_user_framebuffer_dirty(struct drm_framebuffer *fb,
 	if (!atomic_read(&front->bits))
 		return 0;
 
-	if (dma_resv_test_signaled(obj->base.resv, dma_resv_usage_rw(false)))
+	if (dma_resv_test_signaled(intel_bo_to_drm_bo(obj)->resv, dma_resv_usage_rw(false)))
 		goto flush;
 
-	ret = dma_resv_get_singleton(obj->base.resv, dma_resv_usage_rw(false),
+	ret = dma_resv_get_singleton(intel_bo_to_drm_bo(obj)->resv, dma_resv_usage_rw(false),
 				     &fence);
 	if (ret || !fence)
 		goto flush;