regulator: hisilicon: use the correct HiSilicon copyright

s/Hisilicon/HiSilicon/.
It should use capital S, according to the official website
https://www.hisilicon.com/en

.

Signed-off-by: Hao Fang <fanghao11@huawei.com>
Link: https://lore.kernel.org/r/1621679151-15617-1-git-send-email-fanghao11@huawei.com


Signed-off-by: Mark Brown <broonie@kernel.org>