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: Simon Glass <sjg@chromium.org>
Acked-by: Anatolij Gustschin <agust@denx.de>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-on: Beaver, Jetson-TK1
diff --git a/drivers/video/vidconsole-uclass.c b/drivers/video/vidconsole-uclass.c
index e9a90b1..b5afd72 100644
--- a/drivers/video/vidconsole-uclass.c
+++ b/drivers/video/vidconsole-uclass.c
@@ -77,6 +77,7 @@
 		if (priv->ycur < 0)
 			priv->ycur = 0;
 	}
+	video_sync(dev->parent);
 
 	return 0;
 }