drm/mediatek: add function to return RDMA layer number

This patch add function to return RDMA layer number

RDMA always has one layer.
Signed-off-by: Stu Hsieh <stu.hsieh@mediatek.com>
Signed-off-by: CK Hu <ck.hu@mediatek.com>

drivers/gpu/drm/mediatek/mtk_disp_rdma.c

@@ -192,6 +192,11 @@ static unsigned int rdma_fmt_convert(struct mtk_disp_rdma *rdma,
 	}
 }
 
+static unsigned int mtk_rdma_layer_nr(struct mtk_ddp_comp *comp)
+{
+	return 1;
+}
+
 static void mtk_rdma_layer_config(struct mtk_ddp_comp *comp, unsigned int idx,
 				  struct mtk_plane_state *state)
 {
@@ -229,6 +234,7 @@ static const struct mtk_ddp_comp_funcs mtk_disp_rdma_funcs = {
 	.stop = mtk_rdma_stop,
 	.enable_vblank = mtk_rdma_enable_vblank,
 	.disable_vblank = mtk_rdma_disable_vblank,
+	.layer_nr = mtk_rdma_layer_nr,
 	.layer_config = mtk_rdma_layer_config,
 };