add Alphascale to vendor-prefixes.txt

this company already provided some products, so it make sense to add
them to vendor-prefixes.txt list
Signed-off-by: NOleksij Rempel <linux@rempel-privat.de>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NOlof Johansson <olof@lixom.net>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -11,6 +11,7 @@ adi	Analog Devices, Inc.
 aeroflexgaisler	Aeroflex Gaisler AB
 ak	Asahi Kasei Corp.
 allwinner	Allwinner Technology Co., Ltd.
+alphascale	AlphaScale Integrated Circuits Systems, Inc.
 altr	Altera Corp.
 amcc	Applied Micro Circuits Corporation (APM, formally AMCC)
 amd	Advanced Micro Devices (AMD), Inc.