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

Mediatek MT65xx & MT81xx SoC

modulename: mediatek.ko

and/or

irq-mtk-sysirq.ko

configname: CONFIG_ARCH_MEDIATEK

Linux Kernel Configuration
└─>Mediatek MT65xx & MT81xx SoC
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Support for Mediatek MT65xx & MT81xx SoCs

source code:
/arch/arm/mach-mediatek/mediatek.c