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: NFabio Estevam <festevam@gmail.com>
Reviewed-by: NPeng Fan <peng.fan@nxp.com>

configs/mx6ul_14x14_evk_defconfig

@@ -56,6 +56,7 @@ CONFIG_SPI_FLASH_STMICRO=y
 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

include/configs/mx6ul_14x14_evk.h

@@ -172,7 +172,6 @@
 #endif
 
 #ifdef CONFIG_CMD_NET
-#define CONFIG_FEC_MXC
 #define CONFIG_FEC_ENET_DEV		1
 
 #if (CONFIG_FEC_ENET_DEV == 0)