nvme-fc: fix race between error recovery and creating association

There is a small race window between nvme-fc association creation and error
recovery. Fix this race condition by protecting accessing to controller
state and ASSOC_FAILED flag under nvme-fc controller lock.

Signed-off-by: Michael Liang <mliang@purestorage.com>
Reviewed-by: Caleb Sander <csander@purestorage.com>
Reviewed-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>