CONFIG_CMDLINE_OVERRIDE is not available for the selected architecture x86.
Result is shown for architecture mips

Built-in command line overrides firmware arguments

configname: CONFIG_CMDLINE_OVERRIDE

Linux Kernel Configuration
└─>Built-in command line overrides firmware arguments
In linux kernel since version 2.6.28 (release Date: 2008-12-24)
By setting this option to 'Y' you will have your kernel ignore
command line arguments from firmware or second stage bootloader.
Instead, the built-in command line will be used exclusively.

Normally, you will choose 'N' here.