scsi: ses: Fix unsigned comparison with less than zero

Fix the following coccicheck warning:

./drivers/scsi/ses.c:137:10-16: WARNING: Unsigned expression compared
with zero: result > 0.

Link: https://lore.kernel.org/r/1632477113-90378-1-git-send-email-jiapeng.chong@linux.alibaba.com


Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>