arm: dart6ul: enable DM_ETH for the dart6ul

This patch converts the dart6ul ethernet support to DM_ETH and cleans
up the legacy ethernet code. The clean up, more specifically:

* moves the fec2 node and pin definition to the carrier board DTS
  since the phy associated with it is on the carrier board and not on
  the SoM;
* add the reset pin associated to each phy;
* separate the ethernet, mdio and reset pins of each fec so that they
  are easier to reference;
* add clock properties to the phy nodes since they are connected to the
  50Mhz ENET[12]_TX_CLK clock of the SoC;
* remove CONFIG_BOARD_EARLY_INIT_F since the function is now empty.

Signed-off-by: Marc Ferland <ferlandm@amotus.ca>
diff --git a/configs/variscite_dart6ul_defconfig b/configs/variscite_dart6ul_defconfig
index 7218825..b1afcf1 100644
--- a/configs/variscite_dart6ul_defconfig
+++ b/configs/variscite_dart6ul_defconfig
@@ -18,7 +18,6 @@
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/mach-imx/spl_sd.cfg"
 CONFIG_BOOTDELAY=3
 # CONFIG_USE_BOOTCOMMAND is not set
-CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL_USB_HOST_SUPPORT=y
 CONFIG_SPL_WATCHDOG_SUPPORT=y
 CONFIG_CMD_DM=y
@@ -42,6 +41,7 @@
 CONFIG_MTD=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y
+CONFIG_DM_ETH_PHY=y
 CONFIG_FEC_MXC=y
 CONFIG_MII=y
 CONFIG_PINCTRL=y