CONFIG_MACH_ACS5K is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_MACH_ACS5K.
Result is shown for kernelversion 6.9.9

Brivo Systems LLC, ACS-5000 Master board

modulename: board-acs5k.ko

configname: CONFIG_MACH_ACS5K

Linux Kernel Configuration
└─>Kendin/Micrel KS8695 Implementations
└─>Brivo Systems LLC, ACS-5000 Master board
In linux kernel since version 2.6.30 (release Date: 2009-06-09)  
say 'Y' here if you want your kernel to run on the Brivo
Systems LLC, ACS-5000 Master board.

source code:
arch/arm/mach-ks8695/board-acs5k.c