USB: adutux: NULL dereferences on disconnect

commit fc625960edecfb57e62c2975d1f155155e28e6ba upstream.

Both "dev->udev" and "interface->dev" are NULL.  These printks are not
very interesting so I just deleted them.

Fixes: 03270634e242 ('USB: Add ADU support for Ontrak ADU devices')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>