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_mmc.c b/common/cmd_mmc.c
index 698157f..e5f5e94 100644
--- a/common/cmd_mmc.c
+++ b/common/cmd_mmc.c
@@ -32,10 +32,8 @@
 {
 	int dev;
 
-	if (argc < 2) {
-		cmd_usage(cmdtp);
-		return 1;
-	}
+	if (argc < 2)
+		return cmd_usage(cmdtp);
 
 	if (strcmp(argv[1], "init") == 0) {
 		if (argc == 2) {
@@ -46,8 +44,7 @@
 		} else if (argc == 3) {
 			dev = (int)simple_strtoul(argv[2], NULL, 10);
 		} else {
-			cmd_usage(cmdtp);
-			return 1;
+			return cmd_usage(cmdtp);
 		}
 
 		if (mmc_legacy_init(dev) != 0) {
@@ -72,14 +69,12 @@
 #endif
 			curr_device = dev;
 		} else {
-			cmd_usage(cmdtp);
-			return 1;
+			return cmd_usage(cmdtp);
 		}
 
 		printf("mmc%d is current device\n", curr_device);
 	} else {
-		cmd_usage(cmdtp);
-		return 1;
+		return cmd_usage(cmdtp);
 	}
 
 	return 0;