dt: Add vendor prefix 'holt'

Add Holt Integrated Circuits, Inc. to the list of device tree vendor
prefixes

Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -99,6 +99,7 @@ himax	Himax Technologies, Inc.
 hisilicon	Hisilicon Limited.
 hit	Hitachi Ltd.
 hitex	Hitex Development Tools
+holt	Holt Integrated Circuits, Inc.
 honeywell	Honeywell
 hp	Hewlett Packard
 i2se	I2SE GmbH