CONFIG_SOC_VIRT is not available for the selected architecture x86.
Result is shown for architecture riscv
QEMU Virt Machine
configname: CONFIG_SOC_VIRT
Linux Kernel Configuration
└─>SoC selection
└─>QEMU Virt Machine
In linux kernel since version 5.1 (release Date: 2019-05-05)
This enables support for QEMU Virt Machine.