if_ether: add define for 1588 aka Timesync

This patch adds ETH_P_1588 protocol ID define.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_ether.h

@@ -78,6 +78,7 @@
 #define ETH_P_PAE	0x888E		/* Port Access Entity (IEEE 802.1X) */
 #define ETH_P_AOE	0x88A2		/* ATA over Ethernet		*/
 #define ETH_P_TIPC	0x88CA		/* TIPC 			*/
+#define ETH_P_1588	0x88F7		/* IEEE 1588 Timesync */
 #define ETH_P_FCOE	0x8906		/* Fibre Channel over Ethernet  */
 #define ETH_P_FIP	0x8914		/* FCoE Initialization Protocol */
 #define ETH_P_EDSA	0xDADA		/* Ethertype DSA [ NOT AN OFFICIALLY REGISTERED ID ] */