configs: P2020RDB: Enable DM_ETH config

Enable the DM_ETH and DM_MDIO config.

On P2020RDB, the eTSEC1 is connecting with a switch VSC7385,
so also enable the fixed PHY support.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/configs/P2020RDB-PC_36BIT_defconfig b/configs/P2020RDB-PC_36BIT_defconfig
index 60827e4..08f7012 100644
--- a/configs/P2020RDB-PC_36BIT_defconfig
+++ b/configs/P2020RDB-PC_36BIT_defconfig
@@ -53,6 +53,7 @@
 CONFIG_SF_DEFAULT_MODE=0
 CONFIG_SF_DEFAULT_SPEED=10000000
 CONFIG_SPI_FLASH_SPANSION=y
+CONFIG_PHY_FIXED=y
 CONFIG_PHY_ATHEROS=y
 CONFIG_PHY_BROADCOM=y
 CONFIG_PHY_DAVICOM=y
@@ -64,8 +65,10 @@
 CONFIG_PHY_VITESSE=y
 CONFIG_PHY_GIGE=y
 CONFIG_E1000=y
+CONFIG_DM_ETH=y
 CONFIG_MII=y
 CONFIG_TSEC_ENET=y
+CONFIG_DM_MDIO=y
 CONFIG_DM_PCI=y
 CONFIG_DM_PCI_COMPAT=y
 CONFIG_PCIE_FSL=y