of: add picochip vendor prefix

Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -30,6 +30,7 @@ national	National Semiconductor
 nintendo	Nintendo
 nvidia	NVIDIA
 nxp	NXP Semiconductors
+picochip	Picochip Ltd
 powervr	Imagination Technologies
 qcom	Qualcomm, Inc.
 ramtron	Ramtron International