[patch] usbnet: fix kconfig for usbnet drivers

Fix kernel build error: drivers/built-in.o: In function `usbnet_set_settings': : undefined reference to `mii_ethtool_sset' drivers/built-in.o: In function `usbnet_get_settings': : undefined reference to `mii_ethtool_gset' drivers/built-in.o: In function `usbnet_get_link': : undefined

[patch] usbnet: fix kconfig for usbnet drivers

Fix kernel build error: drivers/built-in.o: In function `usbnet_set_settings': : undefined reference to `mii_ethtool_sset' drivers/built-in.o: In function `usbnet_get_settings': : undefined reference to `mii_ethtool_gset' drivers/built-in.o: In function `usbnet_get_link': : undefined