scsi: message: fusion: Remove unused sas_persist_task work

MPT_ADAPTER->sas_persist_task is no longer used since commit 3eb0822c
("[SCSI] mpt fusion: Firmware event implementation using seperate
WorkQueue").

Link: https://lore.kernel.org/r/b2ca2164-5347-8ec1-d8b6-3225df864173@I-love.SAKURA.ne.jp


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