CONFIG_MACH_SUN7I is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Allwinner A20 (sun7i) SoCs support

configname: CONFIG_MACH_SUN7I

Linux Kernel Configuration
└─>Allwinner SoCs
└─>Allwinner A20 (sun7i) SoCs support
In linux kernel since version 3.10 (release Date: 2013-06-30)