drm/panel: simple: Fix g121x1_l03 hsync/vsync polarity

Set hsync/vsync to active low for g121x1_l03 panel to match the
recommended setting in the datasheet.

Signed-off-by: Akshay Bhat <akshay.bhat@timesys.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index f88a631..7a65cc8 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -847,6 +847,7 @@
 	.vsync_end = 768 + 38 + 1,
 	.vtotal = 768 + 38 + 1 + 0,
 	.vrefresh = 60,
+	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
 };
 
 static const struct panel_desc innolux_g121x1_l03 = {