Instead of each transport using it's own workqueue, export
a single nvme-core workqueue and use that instead.
In the future, this will help us moving towards some unification
if controller setup/teardown flows.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
9a6327d2f2