scsi: hisi_sas: Fix pointer usage error in show debugfs IOST/ITCT

Fix how the pointer is set in hisi_sas_debugfs_iost_show() and
hisi_sas_debugfs_itct_show().

Signed-off-by: Luo Jiaxing <luojiaxing@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>