ntb_transport: Pick an unused queue

Fix typo causing ntb_transport_create_queue to select the first
queue every time, instead of using the next free queue.

Signed-off-by: Thomas VanSelus <tvanselus@xes-inc.com>
Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>
Fixes: fce8a7bb

 ("PCI-Express Non-Transparent Bridge Support")
Signed-off-by: Jon Mason <jdmason@kudzu.us>