devicetree: bindings: add sandisk to the vendor prefixes

Add sandisk to the list of vendors. This prefix should be used
also for companies absorbed by Sandisk, like M-Systems.
Signed-off-by: NRobert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -127,6 +127,7 @@ renesas	Renesas Electronics Corporation
 ricoh	Ricoh Co. Ltd.
 rockchip	Fuzhou Rockchip Electronics Co., Ltd
 samsung	Samsung Semiconductor
+sandisk	Sandisk Corporation
 sbs	Smart Battery System
 schindler	Schindler
 seagate	Seagate Technology PLC