arm64: Kconfig.platforms: Add config for Nuvoton MA35 platform

Add ARCH_NUVOTON configuration option for Nuvoton MA35 family SoCs.

Signed-off-by: Jacky Huang <ychuang3@nuvoton.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>