CONFIG_KVM_MIPS_VZ is not available for the default architecture x86.
Result is shown for architecture mips

MIPS Virtualization (VZ) ASE

configname: CONFIG_KVM_MIPS_VZ

Virtualization mode
└─> MIPS Virtualization (VZ) ASE

In linux kernel since version 4.2 (release Date: 2015-08-30)  

Use the MIPS Virtualization (VZ) ASE to virtualize guests. This
supports running unmodified guest kernels (with CONFIG_KVM_GUEST=n),
but requires hardware support.