scsi: pm8001: Fix use-after-free for aborted TMF sas_task

In the Linux kernel, the following vulnerability has been resolved: scsi: pm8001: Fix use-after-free for aborted TMF sas_task Currently a use-after-free may occur if a TMF sas_task is aborted before we handle the IO completion in mpi_ssp_completion(). The abort occurs due to timeout. When the timeout occurs, the SAS_TASK_STATE_ABORTED flag is set and the sas_task is freed in pm8001_exec_internal_tmf_task(). However, if the I/O completion occurs later, the I/O completion still thinks that the sas_task is available. Fix this by clearing the ccb->task if the TMF times out - the I/O completion handler does nothing if this pointer is cleared.