mx6cuboxi: Convert to DM_ETH

Migration to DM_ETH is mandatory, so convert mx6cuboxi to Ethernet
Driver Model.

This also brings the benefit of restoring Ethernet functionality.

Reported-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Tested-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/mx6cuboxi_defconfig b/configs/mx6cuboxi_defconfig
index df7e461..568cfce 100644
--- a/configs/mx6cuboxi_defconfig
+++ b/configs/mx6cuboxi_defconfig
@@ -50,6 +50,9 @@
 CONFIG_FSL_USDHC=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_ATHEROS=y
+CONFIG_DM_ETH=y
+CONFIG_FEC_MXC=y
+CONFIG_RGMII=y
 CONFIG_MII=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX6=y