[CAN]: Allocate protocol numbers for PF_CAN

This patch adds a protocol/address family number, ARP hardware type,
ethernet packet type, and a line discipline number for the SocketCAN
implementation.

Signed-off-by: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
Signed-off-by: Urs Thuermann <urs.thuermann@volkswagen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_arp.h b/include/linux/if_arp.h
index ed7b93c..296e8e8 100644
--- a/include/linux/if_arp.h
+++ b/include/linux/if_arp.h
@@ -52,6 +52,7 @@
 #define ARPHRD_ROSE	270
 #define ARPHRD_X25	271		/* CCITT X.25			*/
 #define ARPHRD_HWX25	272		/* Boards with X.25 in firmware	*/
+#define ARPHRD_CAN	280		/* Controller Area Network      */
 #define ARPHRD_PPP	512
 #define ARPHRD_CISCO	513		/* Cisco HDLC	 		*/
 #define ARPHRD_HDLC	ARPHRD_CISCO