cmd_usage(): simplify return code handling

Lots of code use this construct:

	cmd_usage(cmdtp);
	return 1;

Change cmd_usage() let it return 1 - then we can replace all these
ocurrances by

	return cmd_usage(cmdtp);

This fixes a few places with incorrect return code handling, too.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/common/cmd_mii.c b/common/cmd_mii.c
index 1619a25..bb94186 100644
--- a/common/cmd_mii.c
+++ b/common/cmd_mii.c
@@ -301,10 +301,8 @@
 	int		rcode = 0;
 	char		*devname;
 
-	if (argc < 2) {
-		cmd_usage(cmdtp);
-		return 1;
-	}
+	if (argc < 2)
+		return cmd_usage(cmdtp);
 
 #if defined(CONFIG_MII_INIT)
 	mii_init ();
@@ -431,8 +429,7 @@
 		else
 			miiphy_set_current_dev (argv[2]);
 	} else {
-		cmd_usage(cmdtp);
-		return 1;
+		return cmd_usage(cmdtp);
 	}
 
 	/*