if_ether: add new Ethernet Protocol ID for af_iucv

Add a new ethertype for af_iucv over s/390 HiperSockets transport. Since
HiperSockets is not a real ethernet hw this is not an officially registered ID.

Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>