Compilation fix. MAC_FMT is required for
drivers/net/wireless/libertas/debugfs.c

The problem has been introduced by the
commit 4b326fa2167d4ee2d722bff4e241fae299e32442
Author: Michael Chan <mchan@broadcom.com>
Date:   Mon Dec 24 21:28:09 2007 -0800

diff --git a/include/linux/if_ether.h b/include/linux/if_ether.h
index 7a1e011..2928586 100644
--- a/include/linux/if_ether.h
+++ b/include/linux/if_ether.h
@@ -129,6 +129,7 @@ extern ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len);
 /*
  *	Display a 6 byte device address (MAC) in a readable format.
  */
+#define MAC_FMT "%02x:%02x:%02x:%02x:%02x:%02x"
 extern char *print_mac(char *buf, const unsigned char *addr);
 #define MAC_BUF_SIZE	18
 #define DECLARE_MAC_BUF(var) char var[MAC_BUF_SIZE] __maybe_unused