[NET]: Introduce and use print_mac() and DECLARE_MAC_BUF()

This is nicer than the MAC_FMT stuff.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_ether.h b/include/linux/if_ether.h
index 3213f6f..0e791e2c 100644
--- a/include/linux/if_ether.h
+++ b/include/linux/if_ether.h
@@ -120,6 +120,14 @@
 #ifdef CONFIG_SYSCTL
 extern struct ctl_table ether_table[];
 #endif
+
+/*
+ *	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 u8 *addr);
+#define DECLARE_MAC_BUF(var) char var[18] __maybe_unused
+
 #endif
 
 #endif	/* _LINUX_IF_ETHER_H */