scsi: sym53c8xx: fix typos in comments

Fix the typo "GPOI" -> "GPIO" in comment.

Link: https://lore.kernel.org/r/20191212023556.72618-1-chenzhou10@huawei.com


Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>