Update the TCP LRO code to handle both encrypted and un-encrypted traffic.

Encrypted and un-encrypted traffic needs to be coalesced separately.
Split the 16-bit lro_type field in the address information into two
8-bit fields, and then use the last 8-bit field for flags, which among
other indicate if the received mbuf is encrypted or un-encrypted.

Differential Revision: https://reviews.freebsd.org/D31377
Reviewed by: gallatin
MFC after: 1 week
Sponsored by: NVIDIA Networking