net/fec: add dual fec support for mx28

This patch is to add mx28 dual fec support. Here are some key notes
for mx28 fec controller.

 - The mx28 fec controller naming ENET-MAC is a different IP from FEC
   used on other i.mx variants.  But they are basically compatible
   on software interface, so it's possible to share the same driver.
 - ENET-MAC design on mx28 made an improper assumption that it runs
   on a big-endian system. As the result, driver has to swap every
   frame going to and coming from the controller.
 - The external phys can only be configured by fec0, which means fec1
   can not work independently and both phys need to be configured by
   mii_bus attached on fec0.
 - ENET-MAC reset will get mac address registers reset too.
 - ENET-MAC MII/RMII mode and 10M/100M speed are configured
   differently FEC.
 - ETHER_EN bit must be set to get ENET-MAC interrupt work.

Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 3fda24a..5780dad 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -1944,18 +1944,19 @@
 config FEC
 	bool "FEC ethernet controller (of ColdFire and some i.MX CPUs)"
 	depends on M523x || M527x || M5272 || M528x || M520x || M532x || \
-		MACH_MX27 || ARCH_MX35 || ARCH_MX25 || ARCH_MX5
+		MACH_MX27 || ARCH_MX35 || ARCH_MX25 || ARCH_MX5 || SOC_IMX28
 	select PHYLIB
 	help
 	  Say Y here if you want to use the built-in 10/100 Fast ethernet
 	  controller on some Motorola ColdFire and Freescale i.MX processors.
 
 config FEC2
-	bool "Second FEC ethernet controller (on some ColdFire CPUs)"
+	bool "Second FEC ethernet controller"
 	depends on FEC
 	help
 	  Say Y here if you want to use the second built-in 10/100 Fast
-	  ethernet controller on some Motorola ColdFire processors.
+	  ethernet controller on some Motorola ColdFire and Freescale
+	  i.MX processors.
 
 config FEC_MPC52xx
 	tristate "MPC52xx FEC driver"