of: Add Panasonic Corporation vendor prefix

Use "panasonic" as the vendor prefix for the Panasonic Corporation.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -48,6 +48,7 @@ nintendo	Nintendo
 nvidia	NVIDIA
 nxp	NXP Semiconductors
 onnn	ON Semiconductor Corp.
+panasonic	Panasonic Corporation
 phytec	PHYTEC Messtechnik GmbH
 picochip	Picochip Ltd
 powervr	PowerVR (deprecated, use img)