CONFIG_ARCH_BCM_53573 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Broadcom BCM53573 SoC series support

modulename: clk-bcm53573-ilp.ko

configname: CONFIG_ARCH_BCM_53573

Linux Kernel Configuration
└─>Broadcom SoC Support
└─>Broadcom BCM53573 SoC series support
In linux kernel since version 4.1 (release Date: 2015-06-21)  
BCM53573 series is set of SoCs using ARM Cortex-A7 CPUs with wireless
embedded in the chipset.
This SoC line is mostly used in home routers and is some cheaper
alternative for Northstar family.

The base chip is BCM53573 and there are some packaging modifications
like BCM47189 and BCM47452.

source code: