RDMA/cxgb4: Don't change QP state outside EP lock

Concurrent ingress CLOSE and ULP ABORT operations causes a crash due
to a race condition where the close path releases the EP lock and then
tries to move the QP state to CLOSED.  This must be done inside the EP
lock to avoid the race.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>