RDMA/mana_ib: drain QP references after partial table insertion

In the Linux kernel, the following vulnerability has been resolved: RDMA/mana_ib: drain QP references after partial table insertion mana_table_store_ud_qp() publishes a QP at its send-queue id before inserting the receive-queue id, dropping the XArray lock between the two xa_insert_irq() calls. A concurrent completion handler can look up the QP and take a transient reference. When the second insertion fails, the rollback erased only the send-queue entry and returned, leaving both the initial table reference and the transient reference outstanding while RDMA core frees the QP, causing a use-after-free. Drain the reference as normal destruction does: drop the initial reference and wait for qp->free, releasing the QP only after every concurrent lookup returns its reference.