default or selected kernelversion does not have config value CONFIG_8xx_WDT.
Result is shown for kernelversion 5.19-rc1

MPC8xx Watchdog Timer

modulename: mpc8xx_wdt.ko

configname: CONFIG_8xx_WDT

Linux Kernel Configuration
└─>Device Drivers
└─>Watchdog Timer Support
└─>MPC8xx Watchdog Timer
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
source code:
drivers/watchdog/mpc8xx_wdt.c