A very simple test for DM_MDIO, mimicks a register write/read through the
sandbox bus to a dummy PHY.
Signed-off-by: NAlex Marginean <alexm.osslist@gmail.com>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>
Tested-by: NBin Meng <bmeng.cn@gmail.com>
Acked-by: NJoe Hershberger <joe.hershberger@ni.com>