kernelconfig_penguin
CONFIG_ARCH_BRCMSTB is not available for the default architecture x86.
Result is shown for architecture arm

Broadcom BCM7XXX based boards

configname: CONFIG_ARCH_BRCMSTB

Linux Kernel Configuration
└─> Broadcom SoC Support
└─> Broadcom BCM7XXX based boards

Say Y if you intend to run the kernel on a Broadcom ARM-based STB
chipset.

This enables support for Broadcom ARM-based set-top box chipsets,
including the 7445 family of chips.