CONFIG_MACH_MT7629 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

MediaTek MT7629 SoCs support

configname: CONFIG_MACH_MT7629

Linux Kernel Configuration
└─>MediaTek SoC Support
└─>MediaTek MT7629 SoCs support
In linux kernel since version 5.1 (release Date: 2019-05-05)