of: add vendor prefixes for hisilicon

Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -26,6 +26,7 @@ est	ESTeem Wireless Modems
 fsl	Freescale Semiconductor
 GEFanuc	GE Fanuc Intelligent Platforms Embedded Systems, Inc.
 gef	GE Fanuc Intelligent Platforms Embedded Systems, Inc.
+hisilicon	Hisilicon Limited.
 hp	Hewlett Packard
 ibm	International Business Machines (IBM)
 idt	Integrated Device Technologies, Inc.