If the system is suspended and user disconnects cable to another host
and connects it to a Thunderbolt device instead we get a warning from
driver core about adding duplicate sysfs attribute and adding the new
device fails.

Handle this properly so that we first remove the existing XDomain
connection before adding new devices.

Fixes: d1ff7024 ("thunderbolt: Add support for XDomain discovery protocol")
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: stable@vger.kernel.org