scsi: hisi_sas: Change the value of register SERDES_CFG to increase reliability of hilink

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

With default value of register SERDES_CFG, the link is not stable for
some special disks when running IO. According to soc guys' suggestion,
need to make the bit10~19 value of register SERDES_CFG the max value to
increase the reliability of hilink.
Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: Yupeng Zhou <zhouyupeng1@huawei.com>

Signed-off-by: chenxiang (M) <chenxiang66@hisilicon.com>
Reviewed-by: huangdaode <huangdaode@hisilicon.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>