scsi: advansys: Fix spelling of 'is'

s/isi/is/

Link: https://lore.kernel.org/r/20210326030412.1656-1-qiumibaozi_1@163.com


Signed-off-by: ganjisheng <ganjisheng@yulong.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>