net: ibm_newemac: convert it to use of_get_phy_mode

The patch extends 'enum phy_interface_t' and of_get_phy_mode a little
bit with PHY_INTERFACE_MODE_NA and PHY_INTERFACE_MODE_SMII added,
and then converts ibm_newemac net driver to use of_get_phy_mode
getting phy mode from device tree.

It also resolves the namespace conflict on phy_read/write between
common mdiobus interface and ibm_newemac private one.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: David Miller <davem@davemloft.net>
diff --git a/drivers/net/ibm_newemac/phy.c b/drivers/net/ibm_newemac/phy.c
index ac9d964..ab4e596 100644
--- a/drivers/net/ibm_newemac/phy.c
+++ b/drivers/net/ibm_newemac/phy.c
@@ -28,12 +28,15 @@
 #include "emac.h"
 #include "phy.h"
 
-static inline int phy_read(struct mii_phy *phy, int reg)
+#define phy_read _phy_read
+#define phy_write _phy_write
+
+static inline int _phy_read(struct mii_phy *phy, int reg)
 {
 	return phy->mdio_read(phy->dev, phy->address, reg);
 }
 
-static inline void phy_write(struct mii_phy *phy, int reg, int val)
+static inline void _phy_write(struct mii_phy *phy, int reg, int val)
 {
 	phy->mdio_write(phy->dev, phy->address, reg, val);
 }