sfc: Use generic MDIO functions and definitions

Make use of the newly-added generic MDIO clause 45 support and remove
redundant definitions.

Add an 'efx_' prefix to the remaining driver-specific MDIO functions
and remove arguments which are redundant with efx->mdio.prtad.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/sfc/Kconfig b/drivers/net/sfc/Kconfig
index 12a8296..260aafa 100644
--- a/drivers/net/sfc/Kconfig
+++ b/drivers/net/sfc/Kconfig
@@ -1,7 +1,7 @@
 config SFC
 	tristate "Solarflare Solarstorm SFC4000 support"
 	depends on PCI && INET
-	select MII
+	select MDIO
 	select CRC32
 	select I2C
 	select I2C_ALGOBIT