scsi: qla2xxx: Avoid flush_scheduled_work() usage

Although qla2xxx driver is calling schedule_{,delayed}_work() from 10
locations, I assume that flush_scheduled_work() from qlt_stop_phase1()
needs to flush only works scheduled by qlt_sched_sess_work(), for this loop
continues while "struct qla_tgt"->sess_works_list is not empty.

Link: https://lore.kernel.org/r/133c6723-90b6-5c8b-72b4-cc01eeb3a8c0@I-love.SAKURA.ne.jp


Tested-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>