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/keymile/km_arm/km_arm.c b/board/keymile/km_arm/km_arm.c
index 3a33b5a..d7cbd7a 100644
--- a/board/keymile/km_arm/km_arm.c
+++ b/board/keymile/km_arm/km_arm.c
@@ -186,10 +186,8 @@
 int do_spi_toggle(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	u32 tmp;
-	if (argc < 2) {
-		cmd_usage(cmdtp);
-		return 1;
-	}
+	if (argc < 2)
+		return cmd_usage(cmdtp);
 
 	if ((strcmp(argv[1], "off") == 0)) {
 		printf("SPI FLASH disabled, NAND enabled\n");
@@ -214,8 +212,7 @@
 		tmp = readl(KW_GPIO0_BASE);
 		writel(tmp & (~FLASH_GPIO_PIN) , KW_GPIO0_BASE);
 	} else {
-		cmd_usage(cmdtp);
-		return 1;
+		return cmd_usage(cmdtp);
 	}
 
 	return 0;