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/pcs440ep/pcs440ep.c b/board/pcs440ep/pcs440ep.c
index d7adff2..a61e945 100644
--- a/board/pcs440ep/pcs440ep.c
+++ b/board/pcs440ep/pcs440ep.c
@@ -616,9 +616,8 @@
 	int	rcode = -1;
 
 	if (argc < 2) {
-  usage:
-		cmd_usage(cmdtp);
-		return 1;
+usage:
+		return cmd_usage(cmdtp);
 	}
 
 	if (argc >= 3) {