bnx2x: add CSUM and TSO support for encapsulation protocols

The patch utilizes FW offload capabilities for
encapsulation protocols.

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>