ARM: socfpga: Enable DM ethernet on A10

Enable DM ethernet framework on Arria10, so that the designware GMAC
can be probed from DT as it should be.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chin Liang See <chin.liang.see@intel.com>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>

configs/socfpga_arria10_defconfig

@@ -34,5 +34,7 @@ CONFIG_DWAPB_GPIO=y
 CONFIG_DM_MMC=y
 CONFIG_MTD_DEVICE=y
 CONFIG_MTD_PARTITIONS=y
+CONFIG_DM_ETH=y
+CONFIG_ETH_DESIGNWARE=y
 CONFIG_SPI=y
 CONFIG_USE_TINY_PRINTF=y