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/of/of_net.c b/drivers/of/of_net.c
index cc117db..bb18471 100644
--- a/drivers/of/of_net.c
+++ b/drivers/of/of_net.c
@@ -16,6 +16,7 @@
  * device driver can get phy interface from device tree.
  */
 static const char *phy_modes[] = {
+	[PHY_INTERFACE_MODE_NA]		= "",
 	[PHY_INTERFACE_MODE_MII]	= "mii",
 	[PHY_INTERFACE_MODE_GMII]	= "gmii",
 	[PHY_INTERFACE_MODE_SGMII]	= "sgmii",
@@ -26,6 +27,7 @@
 	[PHY_INTERFACE_MODE_RGMII_RXID]	= "rgmii-rxid",
 	[PHY_INTERFACE_MODE_RGMII_TXID] = "rgmii-txid",
 	[PHY_INTERFACE_MODE_RTBI]	= "rtbi",
+	[PHY_INTERFACE_MODE_SMII]	= "smii",
 };
 
 /**