CONFIG_DEBUG_BCM63XX is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_DEBUG_BCM63XX.
Result is shown for kernelversion 5.4.229

Kernel low-level debugging on BCM63XX UART

configname: CONFIG_DEBUG_BCM63XX

Kernel low-level debugging port
└─>Kernel low-level debugging on BCM63XX UART
In linux kernel since version 3.18 (release Date: 2014-12-07)