Use layer five checksum flags in the mbuf packet header to pass on crypto state.

Use layer five checksum flags in the mbuf packet header to pass on crypto state.

The mbuf protocol flags get cleared between layers, and also it was discovered
that M_DECRYPTED conflicts with M_HASFCS when receiving ethernet patckets.

Add the proper CSUM_TLS_MASK and CSUM_TLS_DECRYPTED defines, and start using
these instead of M_DECRYPTED inside the TCP LRO code.

This change is needed by coming TLS RX hardware offload support patches.

Suggested by:	kib@
Reviewed by:	jhb@
MFC after:	1 week
Sponsored by:	NVIDIA Networking