thunderbolt: No need to read UID of the root switch on resume

The root switch is part of the host controller and cannot be physically
removed, so there is no point of reading UID again on resume in order to
check if the root switch is still the same.

Suggested-by: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>