[PATCH] nvme: don't call blk_mq_{,un}quiesce_tagset when ctrl->tagset is NULL

[Sagi Grimberg]

>> This would be the queue_count version.  I have to say I much prefer
>> the tagset check, as it is self-documenting and matches what
>> nvme_queue_scan, nvme_cancel_tagset and nvme_cancel_admin_tagset
>> do.
> 
> So no comments so far.  Unless I hear more feedback I'd prefer to
> go with the ->tagset checks that matches what the other code is
> doing and also is more readable.

OK, I'm not opposed to that anymore. We can take care of this
area on a different occasion.