dt-bindings: add vendor prefix for NLT Technologies, Ltd.

NLT technologies is the former NEC display business, but changed its
name to NLT Technologies when forming a joint venture with
Shenzhen AVIC OPTOELECTRONICS, Ltd.

Signed-off-by: Lucas Stach <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/devicetree/bindings/vendor-prefixes.txt

···
 newhaven	Newhaven Display International
 ni	National Instruments
 nintendo	Nintendo
+nlt	NLT Technologies, Ltd.
 nokia	Nokia
 nordic	Nordic Semiconductor
 nuvoton	Nuvoton Technology Corporation