net: freescale: fec: add support for optional enet_out clk

Some MX28 boards need the internal enet_out clock to be enabled. So, do
this in the driver iff the clock was referenced via devicetree.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index eb43729..feabcb6a 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -207,6 +207,7 @@
 
 	struct clk *clk_ipg;
 	struct clk *clk_ahb;
+	struct clk *clk_enet_out;
 	struct clk *clk_ptp;
 
 	/* The saved address of a sent-in-place packet/buffer, for skfree(). */