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_nand.c b/common/cmd_nand.c
index 84b6272..0f47a25 100644
--- a/common/cmd_nand.c
+++ b/common/cmd_nand.c
@@ -275,8 +275,7 @@
 	return ret;
 
 usage:
-	cmd_usage(cmdtp);
-	return 1;
+	return cmd_usage(cmdtp);
 }
 
 #endif
@@ -577,8 +576,7 @@
 #endif
 
 usage:
-	cmd_usage(cmdtp);
-	return 1;
+	return cmd_usage(cmdtp);
 }
 
 U_BOOT_CMD(nand, CONFIG_SYS_MAXARGS, 1, do_nand,
@@ -759,9 +757,8 @@
 #if defined(CONFIG_CMD_MTDPARTS)
 usage:
 #endif
-		cmd_usage(cmdtp);
 		show_boot_progress(-53);
-		return 1;
+		return cmd_usage(cmdtp);
 	}
 
 	show_boot_progress(53);