This reverts commit 6971113e.

As Alan pointed out, this really isn't needed as it doesn't handle this
properly.  Ideally this should be handled by the usb-serial core one
day.  So revert it.
Reported-by: NAlan Stern <stern@rowland.harvard.edu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Johan Hovold <jhovold@gmail.com>
Cc: Anton Samokhvalov <pg83@yandex.ru>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>