ixgbe: enable hardware offload for sctp

Inspired by: Vlad Yasevich <vladislav.yasevich@hp.com>

This is the code to enable ixgbe for hardware offload support
of CRC32c on both transmit and receive of SCTP traffic.

only 82599 supports this offload, not 82598.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>