dt-bindings: mips: cpu: Add I-Class I6500 Multiprocessor Core

The MIPS Warrior I-class I6500 was announced by Imagination
Technologies in 2016 and is used in the Mobileye SoC EyeQ5.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>