Standardize command usage messages with cmd_usage()

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/common/cmd_onenand.c b/common/cmd_onenand.c
index 6a2c924..6d43a77 100644
--- a/common/cmd_onenand.c
+++ b/common/cmd_onenand.c
@@ -465,7 +465,7 @@
 	return 0;
 
 usage:
-	printf("Usage:\n%s\n", cmdtp->usage);
+	cmd_usage(cmdtp);
 	return 1;
 }