dt-bindings: use isil prefix for Intersil in vendor-prefixes.txt

This patch fixes DT vendor-prefixes.txt documentation to reference
isil (NASDAQ symbol and the most used prefix inside the kernel) for
Intersil.

It reverts 7c75c1d5 ("dt-bindings: Document deprecated device
vendor name to fix related warning").
Signed-off-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -84,8 +84,7 @@ innolux	Innolux Corporation
 intel	Intel Corporation
 intercontrol	Inter Control Group
 isee	ISEE 2007 S.L.
-isil    Intersil (deprecated, use isl)
-isl	Intersil
+isil	Intersil
 karo	Ka-Ro electronics GmbH
 keymile	Keymile GmbH
 lacie	LaCie