ARM: dts: omap3-devkit8000: Fix CONFIG_DM_ETH warning

Add the missing ethernet node in u-boot dts.

Signed-off-by: Anthoine Bourgeois <anthoine.bourgeois@gmail.com>
diff --git a/configs/devkit8000_defconfig b/configs/devkit8000_defconfig
index 76371e3..a5e9f61 100644
--- a/configs/devkit8000_defconfig
+++ b/configs/devkit8000_defconfig
@@ -84,5 +84,6 @@
 CONFIG_SYS_NAND_BUSWIDTH_16BIT=y
 CONFIG_SYS_NAND_U_BOOT_LOCATIONS=y
 CONFIG_SYS_NAND_U_BOOT_OFFS=0x80000
+CONFIG_DM_ETH=y
 CONFIG_DRIVER_DM9000=y
 CONFIG_JFFS2_NAND=y