scsi: qla2xxx: Avoid double completion of abort command

qla2x00_tmf_sp_done() now deletes the timer that will run
qla2x00_tmf_iocb_timeout(), but doesn't check whether the timer already
expired.  Check the return value from del_timer() to avoid calling
complete() a second time.

Fixes: 4440e46d ("[SCSI] qla2xxx: Add IOCB Abort command asynchronous ...")
Fixes: 1514839b ("scsi: qla2xxx: Fix NULL pointer crash due to active ...")
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Acked-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>