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_bootm.c b/common/cmd_bootm.c
index bf77fb4..adfa6cd 100644
--- a/common/cmd_bootm.c
+++ b/common/cmd_bootm.c
@@ -491,17 +491,14 @@
 			argv++;
 			return bootm_start(cmdtp, flag, argc, argv);
 		}
-	}
-	/* Unrecognized command */
-	else {
-		cmd_usage(cmdtp);
-		return 1;
+	} else {
+		/* Unrecognized command */
+		return cmd_usage(cmdtp);
 	}
 
 	if (images.state >= state) {
 		printf ("Trying to execute a command out of order\n");
-		cmd_usage(cmdtp);
-		return 1;
+		return cmd_usage(cmdtp);
 	}
 
 	images.state |= state;