ARM: hisi: use the correct HiSilicon copyright

s/Hisilicon/HiSilicon/
It should use capital S, according to
https://www.hisilicon.com/en/terms-of-use

.

Signed-off-by: Hao Fang <fanghao11@huawei.com>
Acked-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>