CONFIG_NIOS2_CMDLINE_IGNORE_DTB is not available for thedefaultarchitecture x86.
Result is shown for architecture nios2

Ignore kernel command string from DTB


Linux Kernel Configuration
└─>Processor type and features
└─>Ignore kernel command string from DTB
In linux kernel since version 3.19 (release Date: 2015-02-08)  
Set this to ignore the bootargs property from the devicetree's
chosen node and fall back to CMDLINE if nothing is passed.