IB/hfi1: Fix possible panic during hotplug remove

IB/hfi1: Fix possible panic during hotplug remove

commit 4fdfaef71fced490835145631a795497646f4555 upstream.

During hotplug remove it is possible that the update counters work
might be pending, and may run after memory has been freed.
Cancel the update counters work before freeing memory.

Fixes: 7724105686e7 ("IB/hfi1: add driver files")
Signed-off-by: Douglas Miller <doug.miller@cornelisnetworks.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Link: https://lore.kernel.org/r/169099756100.3927190.15284930454106475280.stgit@awfm-02.cornelisnetworks.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>