CONFIG_NIOS2_DTB_SOURCE is not available for thedefaultarchitecture x86.
Result is shown for architecture nios2
Device tree source file
configname: CONFIG_NIOS2_DTB_SOURCE
Linux Kernel Configuration
└─>Platform options
└─>Device tree source file
In linux kernel since version 3.19 (release Date: 2015-02-08)
Absolute path to the device tree source (dts) file describing your
system.
system.