net: pxa168_eth: Provide phy_interface mode on platform_data

The PXA168 Ethernet IP support MII and RMII connection to its PHY.
Currently, pxa168 platform_data does not provide a way to pass that
and there is one user of pxa168 platform_data (mach-mmp/gplug).
Given the pinctrl settings of gplug it uses RMII, so add and pass
a corresponding phy_interface_t.

Tested-by: Antoine Ténart <antoine.tenart@free-electrons.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/pxa168_eth.h b/include/linux/pxa168_eth.h
index 18d75e7..37c3811 100644
--- a/include/linux/pxa168_eth.h
+++ b/include/linux/pxa168_eth.h
@@ -13,6 +13,7 @@
 	 */
 	int	speed;		/* 0, SPEED_10, SPEED_100 */
 	int	duplex;		/* DUPLEX_HALF or DUPLEX_FULL */
+	phy_interface_t intf;
 
 	/*
 	 * Override default RX/TX queue sizes if nonzero.