OF/device-tree: Add some entries to vendor-prefixes.txt

We are currently using 'cavium', 'cortina' and 'st', add them to the
list of known prefixes.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -8,7 +8,9 @@ amcc	Applied Micro Circuits Corporation (APM, formally AMCC)
 apm	Applied Micro Circuits Corporation (APM)
 arm	ARM Ltd.
 atmel	Atmel Corporation
+cavium	Cavium, Inc.
 chrp	Common Hardware Reference Platform
+cortina	Cortina Systems, Inc.
 dallas	Maxim Integrated Products (formerly Dallas Semiconductor)
 denx	Denx Software Engineering
 epson	Seiko Epson Corp.
@@ -36,6 +38,7 @@ schindler	Schindler
 sil	Silicon Image
 simtek
 sirf	SiRF Technology, Inc.
+st	STMicroelectronics
 stericsson	ST-Ericsson
 ti	Texas Instruments
 xlnx	Xilinx