doc: fix HiSilicon copyright syntax

[ upstream commit be1650f ]

This patch fixes HiSilicon copyright syntax.

According to the suggestion of our legal department,
to standardize the copyright license of our code to
avoid potential copyright risks, we make a unified
modification to the "Hisilicon", which was nonstandard,
in the main modules we maintain.

We change it to "HiSilicon", which is consistent with
the terms used on the following official website:
https://www.hisilicon.com/en/terms-of-use.

Fixes: 565829d ("net/hns3: add build and doc infrastructure")

Signed-off-by: Min Hu (Connor) <humin29@huawei.com>

doc/guides/nics/hns3.rst

@@ -1,12 +1,12 @@
 ..  SPDX-License-Identifier: BSD-3-Clause
-    Copyright(c) 2018-2019 Hisilicon Limited.
+    Copyright(c) 2018-2019 HiSilicon Limited.
 
 HNS3 Poll Mode Driver
 ===============================
 
 The hns3 PMD (**librte_net_hns3**) provides poll mode driver support
-for the inbuilt Hisilicon Network Subsystem(HNS) network engine
-found in the Hisilicon Kunpeng 920 SoC.
+for the inbuilt HiSilicon Network Subsystem(HNS) network engine
+found in the HiSilicon Kunpeng 920 SoC.
 
 Features
 --------