RDMA: Adding ethertype ETH_P_IBOE

Update the if_ether.h with the  ethertype for Infiniband over
Ethernet packets. Also, removing the occurances of 0x8915
from infiniband vendor drivers.

Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>