nvme-pci: Fix async probe remove race

Ensure the controller is not in the NEW state when nvme_probe() exits.
This will always allow a subsequent nvme_remove() to set the state to
DELETING, fixing a potential race between the initial asynchronous probe
and device removal.

Reported-by: Li Zhong <lizhongfs@gmail.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>