of: add vendor prefix for Qualcomm Atheros, Inc.

This prefix will be used in various compatible properties
for the devices from Qualcomm Atheros, Inc.

Cc: Luis R. Rodriguez <rodrigue@qca.qualcomm.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -43,6 +43,7 @@ nxp	NXP Semiconductors
 onnn	ON Semiconductor Corp.
 picochip	Picochip Ltd
 powervr	PowerVR (deprecated, use img)
+qca	Qualcomm Atheros, Inc.
 qcom	Qualcomm, Inc.
 ralink	Mediatek/Ralink Technology Corp.
 ramtron	Ramtron International