CONFIG_MACH_MT6592 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

MediaTek MT6592 SoCs support

configname: CONFIG_MACH_MT6592

Linux Kernel Configuration
└─>MediaTek SoC Support
└─>MediaTek MT6592 SoCs support
In linux kernel since version 4 (release Date: 2015-04-12)