nvme: Fix managing degraded controllers

commit 5bae7f73d378a986 upstream

Upstream is a near rewrite of the async nvme probe that ultimately didn't
even cleanly merge in 4.5. This patch is a much smaller change targeted
to the regression introduced in 4.4.

If a controller is in a degraded mode that needs admin assistence to
recover, we need to leave the controller running. We just want to disable
namespace access without shuting the controller down.

Fixes: 3cf519b5("nvme: merge nvme_dev_start, nvme_dev_resume and nvme_async_probe")

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>