MFC 290175,290633,299206,300895,301898: Various TOE fixes.

MFC 290175,290633,299206,300895,301898: Various TOE fixes.

290175:
cxgbe/tom: decide whether to shove segments or not only if there is
payload to transmit.

290633:
cxgbe/t4_tom: add a knob to the default configuration file to tune
the TOE for LAN operation.  It is possible to set this to other values
(cluster for networks with little loss and really tight RTTs, and wan
for relatively large RTTs and/or lossy networks) depending on the
environment in which the TOE is being used.

None of this affects plain NIC operation in any way.

299206:
Set the correct vnet in TOE event handlers.

300895:
cxgbe/t4_tom: Exempt RDMA connections from a TCP sanity test for now, to
avoid panicking debug kernels.

t4_tom does not keep track of a connection once it switches to ULP mode
iWARP.  If the connection falls out of ULP mode the driver/hardware seq#
etc. are out of sync.  A better fix would be to figure out what the
current seq# are, update the driver's state, and perform all sanity
checks as usual.

301898:
cxgbe/t4_tom:  Fix inverted assertion in r300895.  It is RDMA
connections and not others that are allowed to fail the receive window
check.

git-svn-id: svn://svn.freebsd.org/base/stable/10@308282 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f