scsi: qla2xxx: Hold qpair lock when sending NVMe LS reject

Summary

In the Linux kernel, the following vulnerability has been resolved: scsi: qla2xxx: Hold qpair lock when sending NVMe LS reject qla_nvme_ls_reject_iocb() allocates from and advances the request ring through __qla2x00_alloc_iocbs() (which assumes the hardware_lock is held) and qla2x00_start_iocbs() (which advances the ring and rings the request-in doorbell), but takes no lock itself. Two of its callers invoke it without the producer lock held: - qla_nvme_xmt_ls_rsp(), the NVMe-FC .xmt_ls_rsp transport callback, on its error path, and - qla2xxx_process_purls_pkt(), run from the purex work/DPC context. Both use ha->base_qpair, whose qp_lock_ptr is hardware_lock, so they can run concurrently with normal I/O submission on the base ring and corrupt the ring producer state, leading to duplicated or dropped commands. The third caller, qla2xxx_process_purls_iocb(), runs inside qla24xx_process_response_queue() with the qpair lock already held and is safe; that is also why the lock cannot be taken inside the helper itself (it would recursively re-acquire hardware_lock on the response path). Take qp_lock_ptr around the two unlocked callers and document the helper as caller-locked. Both run in process context, so spin_lock_irqsave() is used and nothing in the locked region sleeps.