nvme-pci: don't share queue maps

Now that the block layer checks if a queue map has any queues inside
it there is no more reason to duplicate the maps for the non-default
types.

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>