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_bmp.c b/common/cmd_bmp.c
index 5ec798c..d51cc55 100644
--- a/common/cmd_bmp.c
+++ b/common/cmd_bmp.c
@@ -102,8 +102,7 @@
 		addr = simple_strtoul(argv[1], NULL, 16);
 		break;
 	default:
-		cmd_usage(cmdtp);
-		return 1;
+		return cmd_usage(cmdtp);
 	}
 
 	return (bmp_info(addr));
@@ -127,8 +126,7 @@
 	        y = simple_strtoul(argv[3], NULL, 10);
 	        break;
 	default:
-		cmd_usage(cmdtp);
-		return 1;
+		return cmd_usage(cmdtp);
 	}
 
 	 return (bmp_display(addr, x, y));
@@ -159,12 +157,10 @@
 
 	c = find_cmd_tbl(argv[0], &cmd_bmp_sub[0], ARRAY_SIZE(cmd_bmp_sub));
 
-	if (c) {
+	if (c)
 		return  c->cmd(cmdtp, flag, argc, argv);
-	} else {
-		cmd_usage(cmdtp);
-		return 1;
-	}
+	else
+		return cmd_usage(cmdtp);
 }
 
 U_BOOT_CMD(