default or selected kernelversion does not have config value CONFIG_SOC_BCM63XX.
Result is shown for kernelversion 6.9.9

Broadcom 63xx SoC drivers

configname: CONFIG_SOC_BCM63XX

Linux Kernel Configuration
└─>Device Drivers
└─>SOC (System On Chip) specific Drivers
└─>Broadcom SoC drivers
└─>Broadcom 63xx SoC drivers
In linux kernel since version 5.1 (release Date: 2019-05-05)  
Enables drivers for the Broadcom 63xx series of chips.
Drivers can be enabled individually within this menu.

If unsure, say N.

depends
CONFIG_BMIPS_GENERIC or CONFIG_COMPILE_TEST

is selected by
CONFIG_BCM63XX_POWER