video: Adjust video_clear() to return an error

All driver-model operation should return an error code. Adjust this
function to do so also.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Anatolij Gustschin <agust@denx.de>

drivers/video/video-uclass.c

@@ -86,7 +86,7 @@ int video_reserve(ulong *addrp)
 	return 0;
 }
 
-void video_clear(struct udevice *dev)
+int video_clear(struct udevice *dev)
 {
 	struct video_priv *priv = dev_get_uclass_priv(dev);
 
@@ -111,6 +111,8 @@ void video_clear(struct udevice *dev)
 		memset(priv->fb, priv->colour_bg, priv->fb_size);
 		break;
 	}
+
+	return 0;
 }
 
 void video_set_default_colors(struct video_priv *priv)

include/video.h

@@ -120,8 +120,9 @@ int video_reserve(ulong *addrp);
  * video_clear() - Clear a device's frame buffer to background color.
  *
  * @dev:	Device to clear
+ * @return 0
  */
-void video_clear(struct udevice *dev);
+int video_clear(struct udevice *dev);
 
 /**
  * video_sync() - Sync a device's frame buffer with its hardware