packet: support for TX time stamps on RAW sockets

Enable the SO_TIMESTAMPING socket infrastructure for raw packet sockets.
We introduce PACKET_TX_TIMESTAMP for the control message cmsg_type.

Similar support for UDP and CAN sockets was added in commit
51f31cabe3ce5345b51e4a4f82138b38c4d5dc91

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index aa57a5f..6ac23ef 100644
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -47,6 +47,7 @@
 #define PACKET_TX_RING			13
 #define PACKET_LOSS			14
 #define PACKET_VNET_HDR			15
+#define PACKET_TX_TIMESTAMP		16
 
 struct tpacket_stats {
 	unsigned int	tp_packets;