scsi: arcmsr: Fix device hot-plug monitoring timer stop

Fix device hot-plug monitoring timer stop.

Link: https://lore.kernel.org/r/969213d4f124e230c3febc01e2b1db291bf4585c.camel@areca.com.tw


Signed-off-by: ching Huang <ching2048@areca.com.tw>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>