dt-bindings: vendor-prefixes: Add Coreriver vendor prefix

Coreriver is a South Korean microcontroller manufacturer:
http://coreriver.com



Signed-off-by: Nick Reitemeyer <nick.reitemeyer@web.de>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200121141525.3404-1-nick.reitemeyer@web.de


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>