thunderbolt: Use maximum USB3 link rate when reclaiming if link is not up

If the USB3 link is not up the actual link rate is 0 so when reclaiming
bandwidth we should look at maximum supported link rate instead.

Cc: stable@vger.kernel.org
Fixes: 0bd680cd ("thunderbolt: Add USB3 bandwidth management")
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>