net: fec: Select the FEC driver by default for i.MX SoCs

Since commit 230dec61 (net/fec: add imx6q enet support) the FEC driver is no 
longer built by default for i.MX SoCs.

Let the FEC driver be built by default again.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Suggested-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/Kconfig

@@ -24,6 +24,7 @@ config FEC
 	bool "FEC ethernet controller (of ColdFire and some i.MX CPUs)"
 	depends on (M523x || M527x || M5272 || M528x || M520x || M532x || \
 		   ARCH_MXC || ARCH_MXS)
+	default ARCH_MXC || ARCH_MXS if ARM
 	select PHYLIB
 	---help---
 	  Say Y here if you want to use the built-in 10/100 Fast ethernet