nvme: fix regression upon hot device removal and insertion

When we validate the new controller id, we want to skip
controllers that are either deleting or dead. Fix the check
to do that and not on the newly added controller.

Fixes: 1b1031ca ("nvme: validate cntlid during controller initialisation")
Reported-by: Jon Derrick <jonathan.derrick@intel.com>
Tested-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>