be2net: Trim padded packets for Lancer

For padded packets, Lancer computes incorrect checksum. The workaround is
to trim such packets. This workaround is mainly for IPv4 packets.

Signed-off-by: Kalesh AP <kalesh.purayil@emulex.com>
Signed-off-by: Somnath Kotur <somnath.kotur@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>