scsi: qla2xxx: Fix response queue over-consumption in __qla_consume_iocb()

In the Linux kernel, the following vulnerability has been resolved: scsi: qla2xxx: Fix response queue over-consumption in __qla_consume_iocb() qla24xx_process_response_queue() advances ring_ptr past the head IOCB before dispatching, so by the time __qla_consume_iocb() runs, ring_ptr already points at the first continuation IOCB. The function however looped purex->entry_count times starting at ring_ptr. As entry_count includes the head, this consumed one entry too many: it stamped RESPONSE_PROCESSED on the next, unrelated IOCB and advanced the ring past it, silently dropping a legitimate firmware response. The head IOCB's signature was also never marked. Mark the head processed and account for it, then consume only the entry_count - 1 continuation IOCBs, matching __qla_copy_purex_to_buffer().