We need to take minimum of both sides of the USB3 link into consideration,
not just the downstream port. Fix this by calling tb_usb3_max_link_rate()
instead.

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