Convert CONFIG_PHYLIB et al to Kconfig

This converts the following to Kconfig:
   CONFIG_PHYLIB
   CONFIG_PHY_ATHEROS
   CONFIG_PHY_GIGE
   CONFIG_MII

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/pico-imx6_defconfig b/configs/pico-imx6_defconfig
index 5390746..20c7d45 100644
--- a/configs/pico-imx6_defconfig
+++ b/configs/pico-imx6_defconfig
@@ -71,6 +71,7 @@
 CONFIG_DM_ETH=y
 CONFIG_FEC_MXC=y
 CONFIG_RGMII=y
+CONFIG_MII=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX6=y
 CONFIG_MXC_UART=y