Jails can cause Chelsio to fail to correetly initialise some offload settings

Details at https://www.ixsystems.com/community/threads/chelsio-interface-being-created-with-txcsum-tso4-tso6-disabled.72568

In some situations, having a jail running can cause errors with Chelsio NICs at boot, and subsequently. Confirmed on 11.3-U2:

At boot (appears immediately after console menu displayed):
tso4 disabled due to -txcsum
tso6 disabled due to -txcsum
bridge0: error setting capabilities on cxgbe0: 35

When attempt made to remedy using ifconfig:
# ifconfig cxgbe0 rxcsum txcsum tso lro
ifconfig: tso: Resource temporarily unavailable

Now reported/confirmed by multiple users, including multiple confirms that not booting (or deleting) the jail resolves the issue.