scsi: lpfc: Prevent 'use after free' memory overwrite in nvmet LS handling

Use-after-free memory overwrite detected. Problem reported
by Ewan Milne at Red Hat after running lpfc target with additional
memory checking enabled.

Race condition when lpfc_nvmet_xmt_ls_rsp_cmp frees the ctxp
memory in interrupt context before lpfc_nvmet_xmt_ls_rsp
clears a field in the ctxp after successfully issuing the wqe.

Remove the unnecessary ctxp write after reposting the rq buffer. The
ctxp->rqb_buffer field is not checked in LS handling after the wqe
is submitted.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reported-by: Ewan Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>