default or selected kernelversion does not have config value CONFIG_BCM63XX_WDT.
Result is shown for kernelversion 6.9.9

Broadcom BCM63xx hardware watchdog

modulename: bcm63xx_wdt.ko

configname: CONFIG_BCM63XX_WDT

Linux Kernel Configuration
└─>Device Drivers
└─>Watchdog Timer Support
└─>Broadcom BCM63xx hardware watchdog
In linux kernel since version 2.6.37 (release Date: 2011-01-04)  
Watchdog driver for the built in watchdog hardware in Broadcom
BCM63xx SoC.

To compile this driver as a loadable module, choose M here.
The module will be called bcm63xx_wdt.

source code: