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/[e-mail]
Reported-by: Abaci Robot <[e-mail]>
Signed-off-by: Jiapeng Chong <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/ses.c

···
 static int ses_send_diag(struct scsi_device *sdev, int page_code,
 			 void *buf, int bufflen)
 {
-	u32 result;
+	int result;
 
 	unsigned char cmd[] = {
 		SEND_DIAGNOSTIC,