video: Let video_sync to return error value

This patch is preparation for follow up one to support cases where
synchronization can fail.

Suggested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/drivers/video/video_bmp.c b/drivers/video/video_bmp.c
index 5a4d12c..66de223 100644
--- a/drivers/video/video_bmp.c
+++ b/drivers/video/video_bmp.c
@@ -379,8 +379,5 @@
 	if (ret)
 		return log_ret(ret);
 
-	video_sync(dev, false);
-
-	return 0;
+	return video_sync(dev, false);
 }
-