phy: Add MOXA MDIO driver

The MOXA UC-711X hardware(s) has an ethernet controller that seem
to be developed internally. The IC used is "RTL8201CP".

This patch adds an MDIO driver which handles the MII bus.

Signed-off-by: Jonas Jensen <jonas.jensen@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 342561a..9b5d46c 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -154,6 +154,13 @@
 	  interface units of the Allwinner SoC that have an EMAC (A10,
 	  A12, A10s, etc.)
 
+config MDIO_MOXART
+        tristate "MOXA ART MDIO interface support"
+        depends on ARCH_MOXART
+        help
+          This driver supports the MDIO interface found in the network
+          interface units of the MOXA ART SoC
+
 config MDIO_BUS_MUX
 	tristate
 	depends on OF_MDIO