CONFIG_MACH_KOELSCH is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_MACH_KOELSCH.
Result is shown for kernelversion 6.5.1

Koelsch board

modulename: board-koelsch.ko

configname: CONFIG_MACH_KOELSCH

Linux Kernel Configuration
└─>Koelsch board
In linux kernel since version 3.13 (release Date: 2014-01-19)  
source code:
arch/arm/mach-shmobile/board-koelsch.c
selects
CONFIG_USE_OF