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/amcc/makalu/cmd_pll.c b/board/amcc/makalu/cmd_pll.c
index 3c0dc5f..7f75ad7 100644
--- a/board/amcc/makalu/cmd_pll.c
+++ b/board/amcc/makalu/cmd_pll.c
@@ -182,14 +182,14 @@
 {
 	char c = '\0';
 	pll_freq_t pll_freq;
-	if (argc < 2) {
-		cmd_usage(cmdtp);
-		goto ret;
-	}
 
-	for (pll_freq = PLL_ebc20; pll_freq < PLL_TOTAL; pll_freq++)
+	if (argc < 2)
+		return cmd_usage(cmdtp);
+
+	for (pll_freq = PLL_ebc20; pll_freq < PLL_TOTAL; pll_freq++) {
 		if (!strcmp(pll_name[pll_freq], argv[1]))
 			break;
+	}
 
 	switch (pll_freq) {
 	case PLL_ebc20:
@@ -223,8 +223,7 @@
 
 	default:
 		printf("Invalid options\n\n");
-		cmd_usage(cmdtp);
-		goto ret;
+		return cmd_usage(cmdtp);
 	}
 
 	printf("PLL set to %s, "