configs: lx2160aqds_tfa_defconfig: enable DM_ETH and related

Enable CONFIG_DM_ETH and CONFIG_DM_MDIO and related configs for the
LX2160AQDS board.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Razvan Ionut Cirjan <razvanionut.cirjan@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>