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>

common/cmd_itest.c

@@ -165,10 +165,8 @@ int do_itest ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[] )
 	int	value, w;
 
 	/* Validate arguments */
-	if ((argc != 4)){
-		cmd_usage(cmdtp);
-		return 1;
-	}
+	if ((argc != 4))
+		return cmd_usage(cmdtp);
 
 	/* Check for a data width specification.
 	 * Defaults to long (4) if no specification.