cxgb3: Use generic MDIO definitions and mdio_mii_ioctl()

Compile-tested only.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 1ccd547..435bbc9 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -2483,6 +2483,7 @@
 	tristate "Chelsio Communications T3 10Gb Ethernet support"
 	depends on CHELSIO_T3_DEPENDS
 	select FW_LOADER
+	select MDIO
 	help
 	  This driver supports Chelsio T3-based gigabit and 10Gb Ethernet
 	  adapters.