[PATCH] nvme: make controller 'state' sysfs attribute pollable

[Sagi Grimberg]

> So why exposing it then in the first time? I know you don't want dm-mpath in
> NVMe (neither do I) but we have to have something until your patchset and ANA
> is merged. And with this patch it's trivial to build a path checker that just
> looks at the state attribute in sysfs.

Can't we just not use path-checkers for nvme (we already have one in
nvme)?