drm/mediatek: Use correct aliases name for ovl

Aliases property name must include only lowercase and '-', so fix this
in the driver, so we're not tempted to do "ovl_2l0 = &ovl_2l0" in the
device-tree instead of the right one which is "ovl-2l0 = &ovl_2l0".

Fixes: b17bdd0 ("drm/mediatek: add component OVL_2L0")
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c

@@ -359,7 +359,7 @@ static const struct mtk_ddp_comp_funcs ddp_ufoe = {
 
 static const char * const mtk_ddp_comp_stem[MTK_DDP_COMP_TYPE_MAX] = {
 	[MTK_DISP_OVL] = "ovl",
-	[MTK_DISP_OVL_2L] = "ovl_2l",
+	[MTK_DISP_OVL_2L] = "ovl-2l",
 	[MTK_DISP_RDMA] = "rdma",
 	[MTK_DISP_WDMA] = "wdma",
 	[MTK_DISP_COLOR] = "color",