of: Add vendor prefix for ROHM Semiconductor

ROHM Semiconductor Co., Ltd. offer PMICs, touchscreen controllers etc.
http://www.rohm.com/web/global/Signed-off-by: NMarek Vasut <marek.vasut+renesas@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -260,6 +260,7 @@ richtek	Richtek Technology Corporation
 ricoh	Ricoh Co. Ltd.
 rikomagic	Rikomagic Tech Corp. Ltd
 rockchip	Fuzhou Rockchip Electronics Co., Ltd
+rohm	ROHM Semiconductor Co., Ltd
 samsung	Samsung Semiconductor
 samtec	Samtec/Softing company
 sandisk	Sandisk Corporation