be2net: Checksum field valid only for TCP/UDP

L4 checksum field is valid only for TCP/UDP packets in Lancer

Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@emulex.com>
Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: Subramanian Seetharaman <subbu.seetharaman@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>