drm/mediatek: Add mbox_free_channel in mtk_drm_crtc_destroy

Add mbox_free_channel in mtk_drm_crtc_destroy.
Signed-off-by: jason-jh.lin <jason-jh.lin@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -156,6 +156,11 @@ static void mtk_drm_crtc_destroy(struct drm_crtc *crtc)
 	mtk_mutex_put(mtk_crtc->mutex);
 #if IS_REACHABLE(CONFIG_MTK_CMDQ)
 	mtk_drm_cmdq_pkt_destroy(&mtk_crtc->cmdq_handle);
+
+	if (mtk_crtc->cmdq_client.chan) {
+		mbox_free_channel(mtk_crtc->cmdq_client.chan);
+		mtk_crtc->cmdq_client.chan = NULL;
+	}
 #endif
 	drm_crtc_cleanup(crtc);
 }