hostap: fixup strlen() math

In hostap_add_interface() we do:
	sprintf(dev->name, "%s%s", prefix, name);

dev->name has IFNAMSIZ (16) characters.
prefix is local->dev->name.
name is "wds%d"

strlen() returns the number of characters in the string not counting the
NULL so if we have a string with 11 characters we get "12345678901wds%d"
which is 16 characters and a NULL so we're past the end of the array.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/hostap/hostap_main.c

@@ -186,7 +186,7 @@ int prism2_wds_add(local_info_t *local, u8 *remote_addr,
 		return -ENOBUFS;
 
 	/* verify that there is room for wds# postfix in the interface name */
-	if (strlen(local->dev->name) > IFNAMSIZ - 5) {
+	if (strlen(local->dev->name) >= IFNAMSIZ - 5) {
 		printk(KERN_DEBUG "'%s' too long base device name\n",
 		       local->dev->name);
 		return -EINVAL;