mx6ul_evk: Move CONFIG_FEC_MXC to defconfig

CONFIG_FEC_MXC is supported in Kconfig, so it is preferred to
move it to defconfig file.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/configs/mx6ul_14x14_evk_defconfig b/configs/mx6ul_14x14_evk_defconfig
index 53ff67c..2a7f5fd 100644
--- a/configs/mx6ul_14x14_evk_defconfig
+++ b/configs/mx6ul_14x14_evk_defconfig
@@ -56,6 +56,7 @@
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y
 CONFIG_PHY_MICREL_KSZ8XXX=y
+CONFIG_FEC_MXC=y
 CONFIG_DM_ETH=y
 CONFIG_MII=y
 CONFIG_PINCTRL=y