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/drivers/misc/ds4510.c b/drivers/misc/ds4510.c
index 5b33c1f..aa893c3 100644
--- a/drivers/misc/ds4510.c
+++ b/drivers/misc/ds4510.c
@@ -294,8 +294,7 @@
 	if (!c || !((argc == (c->maxargs)) ||
 		(((int)c->cmd == DS4510_CMD_DEVICE) &&
 		 (argc == (c->maxargs - 1))))) {
-		cmd_usage(cmdtp);
-		return 1;
+		return cmd_usage(cmdtp);
 	}
 
 	/* arg2 used as chip addr and pin number */
@@ -366,14 +365,12 @@
 
 #ifdef CONFIG_CMD_DS4510_MEM
 	/* Only eeprom, seeprom, and sram commands should make it here */
-	if (strcmp(argv[2], "read") == 0) {
+	if (strcmp(argv[2], "read") == 0)
 		rw_func = ds4510_mem_read;
-	} else if (strcmp(argv[2], "write") == 0) {
+	else if (strcmp(argv[2], "write") == 0)
 		rw_func = ds4510_mem_write;
-	} else {
-		cmd_usage(cmdtp);
-		return 1;
-	}
+	else
+		return cmd_usage(cmdtp);
 
 	addr = simple_strtoul(argv[3], NULL, 16);
 	off += simple_strtoul(argv[4], NULL, 16);