CONFIG_ARCH_MEDIATEK is not available for thedefaultarchitecture x86.
Result is shown for architecture arm64

MediaTek SoC Family

modulename: irq-mtk-sysirq.ko

configname: CONFIG_ARCH_MEDIATEK

Linux Kernel Configuration
└─>Platform selection
└─>MediaTek SoC Family
In linux kernel since version 3.10 (release Date: 2013-06-30)  
This enables support for MediaTek MT27xx, MT65xx, MT76xx
& MT81xx ARMv8 SoCs