meson: odroid-c2: enable Ethernet support through the device tree

Remove the device definition from board file, update the driver with
the new compatible property and update config with necessary options.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/net/designware.c

@@ -737,6 +737,7 @@ static int designware_eth_ofdata_to_platdata(struct udevice *dev)
 static const struct udevice_id designware_eth_ids[] = {
 	{ .compatible = "allwinner,sun7i-a20-gmac" },
 	{ .compatible = "altr,socfpga-stmmac" },
+	{ .compatible = "amlogic,meson6-dwmac" },
 	{ }
 };