Standardize command usage messages with cmd_usage()

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/common/cmd_ext2.c b/common/cmd_ext2.c
index 9c43792..05a053b 100644
--- a/common/cmd_ext2.c
+++ b/common/cmd_ext2.c
@@ -66,7 +66,7 @@
 	int part_length;
 
 	if (argc < 3) {
-		printf ("Usage:\n%s\n", cmdtp->usage);
+		cmd_usage(cmdtp);
 		return(1);
 	}
 	dev = (int)simple_strtoul (argv[2], &ep, 16);
@@ -164,7 +164,7 @@
 		break;
 
 	default:
-		printf ("Usage:\n%s\n", cmdtp->usage);
+		cmd_usage(cmdtp);
 		return(1);
 	}