hdmi: we jsut support 4K 30Hz, limit pixel clock to 300MHz

Change-Id: Ic31e71634f0669bc7734581d823d3338b2bf31db
Signed-off-by: bross1_kuo <bross1_kuo@asus.com>

Author: BrossKuo

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -2305,6 +2305,9 @@ vop_crtc_mode_valid(struct drm_crtc *crtc, const struct drm_display_mode *mode,
 	int request_clock = mode->clock;
 	int clock;
 
+	if (mode->clock >= 300000)
+		return MODE_CLOCK_RANGE;
+
 	if (mode->hdisplay > vop_data->max_output.width)
 		return MODE_BAD_HVALUE;