USB: USB_RTL8150 must select MII

USB_RTL8150 must select MII to avoid link errors.

Stolen from a patch by Randy Dunlap.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>