Revert "drm/mediatek: Use mailbox rx_callback instead of cmdq_task_cb"

This reverts commit c1ec54b7.

Commit c1ec54b7
("drm/mediatek: Use mailbox rx_callback instead of cmdq_task_cb")
would cause numerous mtk cmdq mailbox driver warning:

WARNING: CPU: 0 PID: 0 at drivers/mailbox/mtk-cmdq-mailbox.c:198
cmdq_task_exec_done+0xb8/0xe0

So revert that patch.
Reported-by: Enric Balletbo Serra <eballetbo@gmail.com>
Tested-by: Enric Balletbo Serra <eballetbo@gmail.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -4,8 +4,6 @@
  */
 
 #include <linux/clk.h>
-#include <linux/dma-mapping.h>
-#include <linux/mailbox_controller.h>
 #include <linux/pm_runtime.h>
 #include <linux/soc/mediatek/mtk-cmdq.h>
 #include <linux/soc/mediatek/mtk-mmsys.h>
@@ -224,11 +222,9 @@ struct mtk_ddp_comp *mtk_drm_ddp_comp_for_plane(struct drm_crtc *crtc,
 }
 
 #if IS_REACHABLE(CONFIG_MTK_CMDQ)
-static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
+static void ddp_cmdq_cb(struct cmdq_cb_data data)
 {
-	struct cmdq_cb_data *data = mssg;
-
-	cmdq_pkt_destroy(data->pkt);
+	cmdq_pkt_destroy(data.data);
 }
 #endif
 
@@ -479,12 +475,7 @@ static void mtk_drm_crtc_update_config(struct mtk_drm_crtc *mtk_crtc,
 		cmdq_pkt_wfe(cmdq_handle, mtk_crtc->cmdq_event, false);
 		mtk_crtc_ddp_config(crtc, cmdq_handle);
 		cmdq_pkt_finalize(cmdq_handle);
-		dma_sync_single_for_device(mtk_crtc->cmdq_client->chan->mbox->dev,
-					    cmdq_handle->pa_base,
-					    cmdq_handle->cmd_buf_size,
-					    DMA_TO_DEVICE);
-		mbox_send_message(mtk_crtc->cmdq_client->chan, cmdq_handle);
-		mbox_client_txdone(mtk_crtc->cmdq_client->chan, 0);
+		cmdq_pkt_flush_async(cmdq_handle, ddp_cmdq_cb, cmdq_handle);
 	}
 #endif
 	mtk_crtc->config_updating = false;
@@ -848,7 +839,6 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 	}
 
 	if (mtk_crtc->cmdq_client) {
-		mtk_crtc->cmdq_client->client.rx_callback = ddp_cmdq_cb;
 		ret = of_property_read_u32_index(priv->mutex_node,
 						 "mediatek,gce-events",
 						 drm_crtc_index(&mtk_crtc->base),