dt-bindings: Add vendor prefix for Actions Semi

Actions Semiconductor was listed on NASDAQ as ACTS until Dec 16, 2016.

Cc: mp-cs@actions-semi.com
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NAndreas Färber <afaerber@suse.de>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -5,6 +5,7 @@ using them to avoid name-space collisions.
 
 abcn	Abracon Corporation
 abilis	Abilis Systems
+actions	Actions Semiconductor Co., Ltd.
 active-semi	Active-Semi International Inc
 ad	Avionic Design GmbH
 adapteva	Adapteva, Inc.