scsi: lpfc: Fix list_add() corruption in lpfc_drain_txq()

In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Fix list_add() corruption in lpfc_drain_txq() When parsing the txq list in lpfc_drain_txq(), the driver attempts to pass the requests to the adapter. If such an attempt fails, a local "fail_msg" string is set and a log message output. The job is then added to a completions list for cancellation. Processing of any further jobs from the txq list continues, but since "fail_msg" remains set, jobs are added to the completions list regardless of whether a wqe was passed to the adapter. If successfully added to txcmplq, jobs are added to both lists resulting in list corruption. Fix by clearing the fail_msg string after adding a job to the completions list. This stops the subsequent jobs from being added to the completions list unless they had an appropriate failure.