devicetree: add DPTechnics vendor id

Please see https://www.dptechnics.com/contact for details.
Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Cc: Daan Pape <daan@dptechnics.com>
Cc: devicetree@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12885/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -70,6 +70,7 @@ digilent	Diglent, Inc.
 dlg	Dialog Semiconductor
 dlink	D-Link Corporation
 dmo	Data Modul AG
+dptechnics	DPTechnics
 dragino	Dragino Technology Co., Limited
 ea	Embedded Artists AB
 ebv	EBV Elektronik