Convert cmd_usage() calls in common to use a return value

Change all files in common/ to use CMD_RET_USAGE instead of calling
cmd_usage() directly. I'm not completely sure about this patch since
the code since impact is small (100 byte or so on ARM) and it might
need splitting into smaller patches. But for now here it is.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/cmd_mem.c b/common/cmd_mem.c
index f7e76d6..fa6f599 100644
--- a/common/cmd_mem.c
+++ b/common/cmd_mem.c
@@ -74,7 +74,7 @@
 	length = dp_last_length;
 
 	if (argc < 2)
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 	if ((flag & CMD_FLAG_REPEAT) == 0) {
 		/* New command specified.  Check for a size specification.
@@ -168,7 +168,7 @@
 	int	size;
 
 	if ((argc < 3) || (argc > 4))
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 	/* Check for size specification.
 	*/
@@ -210,7 +210,7 @@
 	ulong count;
 
 	if (argc < 4)
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 	count = simple_strtoul(argv[3], NULL, 10);
 
@@ -237,7 +237,7 @@
 	ulong count;
 
 	if (argc < 4)
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 	count = simple_strtoul(argv[3], NULL, 10);
 
@@ -266,7 +266,7 @@
 	int     rcode = 0;
 
 	if (argc != 4)
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 	/* Check for size specification.
 	*/
@@ -352,7 +352,7 @@
 	int	size;
 
 	if (argc != 4)
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 	/* Check for size specification.
 	*/
@@ -478,7 +478,7 @@
 	volatile u_char	*cp;
 
 	if (argc < 3)
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 	/* Check for a size spefication.
 	 * Defaults to long if no or incorrect specification.
@@ -547,7 +547,7 @@
 	volatile u_char	*cp;
 
 	if (argc < 4)
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 	/* Check for a size spefication.
 	 * Defaults to long if no or incorrect specification.
@@ -979,7 +979,7 @@
 	int	nbytes, size;
 
 	if (argc != 2)
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 #ifdef CONFIG_BOOT_RETRY_TIME
 	reset_cmd_timeout();	/* got a good command to get here */
@@ -1084,7 +1084,7 @@
 	ulong *ptr;
 
 	if (argc < 3)
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 
 	addr = simple_strtoul (argv[1], NULL, 16);
 	addr += base_address;
@@ -1118,7 +1118,7 @@
 
 	if (argc < 3) {
 usage:
-		return cmd_usage(cmdtp);
+		return CMD_RET_USAGE;
 	}
 
 	av = argv + 1;