nvme-rdma: fix crash when connect rejected

A crash can happened when a connect is rejected.   The host establishes
the connection after received ConnectReply, and then continues to send
the fabrics Connect command.  If the controller does not receive the
ReadyToUse capsule, host may receive a ConnectReject reply.

Call nvme_rdma_destroy_queue_ib after the host received the
RDMA_CM_EVENT_REJECTED event.  Then when the fabrics Connect command
times out, nvme_rdma_timeout calls nvme_rdma_complete_rq to fail the
request.  A crash happenes due to use after free in
nvme_rdma_complete_rq.

nvme_rdma_destroy_queue_ib is redundant when handling the
RDMA_CM_EVENT_REJECTED event as nvme_rdma_destroy_queue_ib is already
called in connection failure handler.

Signed-off-by: Chao Leng <lengchao@huawei.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>