drm/panel: raydium-rm67200: Add missing drm_display_mode flags

Add missing drm_display_mode DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC
flags. Those are used by various bridges(e.g. dw-mipi-dsi) in the
pipeline to correctly configure its sync signals polarity.

Tested on rk3568/rk3576/rk3588 EVB.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250618080955.691048-1-andyshrk@163.com

Author: Andy Yan

drivers/gpu/drm/panel/panel-raydium-rm67200.c

@@ -464,6 +464,7 @@ static const struct raydium_rm67200_panel_info w552793baa_info = {
 		.vtotal = 1952,
 		.width_mm = 68, /* 68.04mm */
 		.height_mm = 121, /* 120.96mm */
+		.flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
 		.type = DRM_MODE_TYPE_DRIVER,
 	},
 	.regulators = w552793baa_regulators,