cxgbe(4): Always report link-down on an abrupt stop.

This fixes a regression in 5241b210a4e1 where the driver stopped
reporting link down after a fatal error unless t4_reset_on_fatal_err was
also set.

Fixes: 5241b210a4e1 cxgbe(4): Basic infrastructure for ULDs to participate in adapter reset.
MFC after: 1 week
Sponsored by: Chelsio Communications