CONFIG_H8300_TIMER8 is not available for thedefaultarchitecture x86.
Result is shown for architecture h8300
default or selected kernelversion does not have config value CONFIG_H8300_TIMER8.
Result is shown for kernelversion 6.2.5

8bit timer (2ch cascade)

modulename: timer8.ko

configname: CONFIG_H8300_TIMER8

Timer
└─>8bit timer (2ch cascade)
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
source code:
arch/h8300/kernel/timer/timer8.c