CONFIG_S5P_SYSMMU is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_S5P_SYSMMU.
Result is shown for kernelversion 5.4.69

SYSMMU support

modulename: sysmmu.ko

configname: CONFIG_S5P_SYSMMU

Linux Kernel Configuration
└─>SYSMMU support
In linux kernel since version 2.6.38.1 (release Date: 2011-03-23)  
This is a System MMU driver for Samsung ARM based Soc.

source code: