Support for STMMAC Selftests

configname: CONFIG_STMMAC_SELFTESTS

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Ethernet driver support
└─>Support for STMMAC Selftests
In linux kernel since version 5.1 (release Date: 2019-05-05)  
This adds support for STMMAC Selftests using ethtool. Enable this
feature if you are facing problems with your HW and submit the test
results to the netdev Mailing List.