net: fec: Enable support for i.MX28 DM_ETH in the fec_mxc.c driver

The fec_mxc.c driver can be reused by i.MX28 when DM_ETH is enabled.
One only needs to add proper compatible and dependency on FEC_MXC in the
Kconfig.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Marek Vasut <marex@denx.de>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 635f8d7..2408c7a 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -213,7 +213,7 @@
 
 config FEC_MXC
 	bool "FEC Ethernet controller"
-	depends on MX5 || MX6 || MX7 || IMX8 || VF610
+	depends on MX28 || MX5 || MX6 || MX7 || IMX8 || VF610
 	help
 	  This driver supports the 10/100 Fast Ethernet controller for
 	  NXP i.MX processors.