Standardize command usage messages with cmd_usage()

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/common/cmd_mii.c b/common/cmd_mii.c
index bcbd7aa..19a7fbd 100644
--- a/common/cmd_mii.c
+++ b/common/cmd_mii.c
@@ -302,7 +302,7 @@
 	char		*devname;
 
 	if (argc < 2) {
-		printf("Usage:\n%s\n", cmdtp->usage);
+		cmd_usage(cmdtp);
 		return 1;
 	}
 
@@ -431,7 +431,7 @@
 		else
 			miiphy_set_current_dev (argv[2]);
 	} else {
-		printf("Usage:\n%s\n", cmdtp->usage);
+		cmd_usage(cmdtp);
 		return 1;
 	}