of: Update Moxa vendor prefix description

Update vendor description to be the full name of the corporate entity
with this prefix

reference:
[1]: http://tmsearch.uspto.gov/bin/showfield?f=doc&state=4806:26uh56.2.5Signed-off-by: NSZ Lin <sz.lin@moxa.com>
Signed-off-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -206,7 +206,7 @@ miramems	MiraMEMS Sensing Technology Co., Ltd.
 mitsubishi	Mitsubishi Electric Corporation
 mosaixtech	Mosaix Technologies, Inc.
 motorola	Motorola, Inc.
-moxa	Moxa
+moxa	Moxa Inc.
 mpl	MPL AG
 mqmaker	mqmaker Inc.
 msi	Micro-Star International Co. Ltd.