dm: video: Sync display on backspace

We should sync the display (e.g. flush cache) when backspace is pressed
to ensure that the character is erased correctly.
Signed-off-by: NSimon Glass <sjg@chromium.org>
Acked-by: NAnatolij Gustschin <agust@denx.de>
Tested-by: NMarcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-on: Beaver, Jetson-TK1

drivers/video/vidconsole-uclass.c

@@ -77,6 +77,7 @@ static int vidconsole_back(struct udevice *dev)
 		if (priv->ycur < 0)
 			priv->ycur = 0;
 	}
+	video_sync(dev->parent);
 
 	return 0;
 }