DSA mock-up Ethernet switch chip support

modulename: dsa_loop.ko

configname: CONFIG_NET_DSA_LOOP

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Distributed Switch Architecture drivers
└─>DSA mock-up Ethernet switch chip support
In linux kernel since version 3.10 (release Date: 2013-06-30)  
This enables support for a fake mock-up switch chip which
exercises the DSA APIs.

source code:
drivers/net/dsa/dsa_loop.c