nvme-fabrics: allow to queue requests for live queues

Right now we are failing requests based on the controller state (which
is checked inline in nvmf_check_ready) however we should definitely
accept requests if the queue is live.

When entering controller reset, we transition the controller into
NVME_CTRL_RESETTING, and then return BLK_STS_RESOURCE for non-mpath
requests (have blk_noretry_request set).

This is also the case for NVME_REQ_USER for the wrong reason. There
shouldn't be any reason for us to reject this I/O in a controller reset.
We do want to prevent passthru commands on the admin queue because we
need the controller to fully initialize first before we let user passthru
admin commands to be issued.

In a non-mpath setup, this means that the requests will simply be
requeued over and over forever not allowing the q_usage_counter to drop
its final reference, causing controller reset to hang if running
concurrently with heavy I/O.

Fixes: 35897b92 ("nvme-fabrics: fix and refine state checks in __nvmf_check_ready")
Reviewed-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>