D02/SAS: remove sts in hisi_sas_slot
D02/SAS: remove sts in hisi_sas_slot

sts is used in timer before, which is not used now.
So remove sts as well.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Zhangfei Gao <b1f7e1a0ab5f2fe9a6663bef87918f01828cf598@linaro.org>
Reviewed-by: Leif Lindholm <a613079f0455438b29e28a9c5b9eb3779a81a33a@linaro.org>

jlinton/OpenPlatformPkg,hisilicon/OpenPlatformPkg,hisilicon/OpenPlatformPkg,jlinton/OpenPlatformPkg