Fix for 4k monitors to limit down screen resolution from auto detecte…

…d 4k down to 2k since older Allwinner devices can't display it.

https://forum.armbian.com/index.php/topic/2864-h3-u-boot-hdmi-driver/?p=20981

patch/u-boot/u-boot-sunxi/4kfix-limit-screen-to-full-hd.patch

@@ -0,0 +1,20 @@
+diff --git a/drivers/video/sunxi_display.c b/drivers/video/sunxi_display.c
+index 6f8ee01..7c12a66 100644
+--- a/drivers/video/sunxi_display.c
++++ b/drivers/video/sunxi_display.c
+@@ -1406,8 +1406,12 @@ void *video_hw_init(void)
+ 		ret = sunxi_hdmi_hpd_detect(hpd_delay);
+ 		if (ret) {
+ 			printf("HDMI connected: ");
+-			if (edid && sunxi_hdmi_edid_get_mode(&custom) == 0)
+-				mode = &custom;
++			if (edid && sunxi_hdmi_edid_get_mode(&custom) == 0) {
++				if((custom.xres <= 1920) && (custom.yres <= 1080))
++					mode = &custom;
++				else
++					mode = &res_mode_init[RES_MODE_1920x1080];
++			}
+ 		} else if (hpd) {
+ 			sunxi_hdmi_shutdown();
+ 			sunxi_display.monitor = sunxi_get_default_mon(false);
+