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

Broadcom Cygnus Support

modulename: bcm_cygnus.ko

configname: CONFIG_ARCH_BCM_CYGNUS

Linux Kernel Configuration
└─>Broadcom SoC Support
└─>Broadcom Cygnus Support
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Enable support for the Cygnus family,
which includes the following variants:
BCM11300, BCM11320, BCM11350, BCM11360,
BCM58300, BCM58302, BCM58303, BCM58305.

source code:
arch/arm/mach-bcm/bcm_cygnus.c