CONFIG_ARCH_BCM is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Broadcom SoC Support

configname: CONFIG_ARCH_BCM

Linux Kernel Configuration
└─>Broadcom SoC Support
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This enables support for Broadcom ARM based SoC chips