mailbox: hisilicon: Use the correct HiSilicon copyright

s/Hisilicon/HiSilicon/.
It should use capital S, according to
https://www.hisilicon.com/en.
Signed-off-by: Hao Fang <fanghao11@huawei.com>
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

drivers/mailbox/hi3660-mailbox.c

 // SPDX-License-Identifier: GPL-2.0
-// Copyright (c) 2017-2018 Hisilicon Limited.
+// Copyright (c) 2017-2018 HiSilicon Limited.
 // Copyright (c) 2017-2018 Linaro Limited.
 
 #include <linux/bitops.h>

drivers/mailbox/hi6220-mailbox.c

@@ -2,7 +2,7 @@
 /*
  * Hisilicon's Hi6220 mailbox driver
  *
- * Copyright (c) 2015 Hisilicon Limited.
+ * Copyright (c) 2015 HiSilicon Limited.
  * Copyright (c) 2015 Linaro Limited.
  *
  * Author: Leo Yan <leo.yan@linaro.org>