dt-bindings: vendor-prefixes: Add YLM

Shenzhen Yangliming Electronic Technology Co., Ltd., abbreviated YLM or
YLMChina, and known as Anbernic in the rest of the world, is a Chinese
manufacturer of handheld game consoles, some of which are known to be
running Linux.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>