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/board/renesas/sh7785lcr/selfcheck.c b/board/renesas/sh7785lcr/selfcheck.c
index 44247c8..6d92c83 100644
--- a/board/renesas/sh7785lcr/selfcheck.c
+++ b/board/renesas/sh7785lcr/selfcheck.c
@@ -112,10 +112,8 @@
 {
 	char *cmd;
 
-	if (argc != 2) {
-		cmd_usage(cmdtp);
-		return 1;
-	}
+	if (argc != 2)
+		return cmd_usage(cmdtp);
 
 	cmd = argv[1];
 	switch (cmd[0]) {
@@ -150,8 +148,7 @@
 		test_net();
 		break;
 	default:
-		cmd_usage(cmdtp);
-		return 1;
+		return cmd_usage(cmdtp);
 	}
 
 	return 0;