configs: update Amlogic Meson G12A, G12B & SM1 configs for MDIO MUX

Use DM_MDIO and the new G12A MDIO MUX driver for G12A, G12B & SM1 boards.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/configs/u200_defconfig b/configs/u200_defconfig
index b0b822b..1fbb78d 100644
--- a/configs/u200_defconfig
+++ b/configs/u200_defconfig
@@ -27,8 +27,9 @@
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_DM_MMC=y
 CONFIG_MMC_MESON_GX=y
-CONFIG_PHY_ADDR_ENABLE=y
-CONFIG_PHY_ADDR=8
+CONFIG_DM_MDIO=y
+CONFIG_DM_MDIO_MUX=y
+CONFIG_MDIO_MUX_MESON_G12A=y
 CONFIG_DM_ETH=y
 CONFIG_ETH_DESIGNWARE=y
 CONFIG_MESON_G12A_USB_PHY=y