[NET]: Let USB_USBNET always select MII.

All this USB_USBNET_MII trickery is simply not worth it considering how
few code it saves.

As a side effect, this also fixes the following compile error reported
by Toralf Förster:

<--  snip  -->

...
  LD      .tmp_vmlinux1
drivers/built-in.o: In function `usbnet_set_settings':
(.text+0xf1876): undefined reference to `mii_ethtool_sset'
drivers/built-in.o: In function `usbnet_get_settings':
(.text+0xf1836): undefined reference to `mii_ethtool_gset'
drivers/built-in.o: In function `usbnet_get_link':
(.text+0xf18d6): undefined reference to `mii_link_ok'
drivers/built-in.o: In function `usbnet_nway_reset':
(.text+0xf18f6): undefined reference to `mii_nway_restart'
make: *** [.tmp_vmlinux1] Error 1

<--  snip  -->

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/usb/Kconfig b/drivers/net/usb/Kconfig
index 5a96d74..a12c9c4 100644
--- a/drivers/net/usb/Kconfig
+++ b/drivers/net/usb/Kconfig
@@ -93,13 +93,9 @@
 	  To compile this driver as a module, choose M here: the
 	  module will be called rtl8150.
 
-config USB_USBNET_MII
-	tristate
-	default n
-
 config USB_USBNET
 	tristate "Multi-purpose USB Networking Framework"
-	select MII if USB_USBNET_MII != n
+	select MII
 	---help---
 	  This driver supports several kinds of network links over USB,
 	  with "minidrivers" built around a common network driver core
@@ -135,7 +131,6 @@
 	tristate "ASIX AX88xxx Based USB 2.0 Ethernet Adapters"
 	depends on USB_USBNET && NET_ETHERNET
 	select CRC32
-	select USB_USBNET_MII
 	default y
 	help
 	  This option adds support for ASIX AX88xxx based USB 2.0
@@ -190,7 +185,6 @@
 	tristate "Davicom DM9601 based USB 1.1 10/100 ethernet devices"
 	depends on USB_USBNET
 	select CRC32
-	select USB_USBNET_MII
 	help
 	  This option adds support for Davicom DM9601 based USB 1.1
 	  10/100 Ethernet adapters.
@@ -225,7 +219,6 @@
 config USB_NET_MCS7830
 	tristate "MosChip MCS7830 based Ethernet adapters"
 	depends on USB_USBNET
-	select USB_USBNET_MII
 	help
 	  Choose this option if you're using a 10/100 Ethernet USB2
 	  adapter based on the MosChip 7830 controller. This includes