RDMA/iw_cxgb4: stop ep timer on close failure

In c4iw_ep_disconnect(), if we start the ep timer to begin a close,
but send_halfclose() fails, we need to stop the timer and send a CLOSE
event up to the IWCM before releasing the resources. Otherwise, we can
crash when the ep timer fires if the ep is referencing a previous instance
of the device. This can happen as part of adapter reset/recovery, for
instance.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>