DT: add vendor prefixes for Ralink

Signed-off-by: NJohn Crispin <blogic@openwrt.org>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -41,6 +41,7 @@ onnn	ON Semiconductor Corp.
 picochip	Picochip Ltd
 powervr	PowerVR (deprecated, use img)
 qcom	Qualcomm, Inc.
+ralink	Mediatek/Ralink Technology Corp.
 ramtron	Ramtron International
 realtek Realtek Semiconductor Corp.
 renesas	Renesas Electronics Corporation