MFC r311569, r311657, and r311949.

MFC r311569, r311657, and r311949.

r311569:
Fix comment in t4_tom.  No functional change.

r311657:
cxgbe/t4_tom: Fix tid accounting.  An offloaded IPv6 connection uses 2
tids, not 1, in the hardware.

r311949:
cxgbe/tom: Add VIMAGE support to the TOE driver.

Active Open:
- Save the socket's vnet at the time of the active open (t4_connect) and
  switch to it when processing the reply (do_act_open_rpl or
  do_act_establish).

Passive Open:
- Save the listening socket's vnet in the driver's listen_ctx and switch
  to it when processing incoming SYNs for the socket.
- Reject SYNs that arrive on an ifnet that's not in the same vnet as the
  listening socket.

CLIP (Compressed Local IPv6) table:
- Add only those IPv6 addresses to the CLIP that are in a vnet
  associated with one of the card's ifnets.

Misc:
- Set vnet from the toepcb when processing TCP state transitions.
- The kernel sets the vnet when calling the driver's output routine
  so t4_push_frames runs in proper vnet context already.  One exception
  is when incoming credits trigger tx within the driver's ithread.  Set
  the vnet explicitly in do_fw4_ack for that case.

Sponsored by:	Chelsio Communications

git-svn-id: svn://svn.freebsd.org/base/stable/10@312117 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f