scsi: qedi: Fix null ref during abort handling

If qedi_process_cmd_cleanup_resp finds the cmd it frees the work and sets
list_tmf_work to NULL, so qedi_tmf_work should check if list_tmf_work is
non-NULL when it wants to force cleanup.

Link: https://lore.kernel.org/r/20210525181821.7617-20-michael.christie@oracle.com


Reviewed-by: Manish Rangankar <mrangankar@marvell.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>