thunderbolt: Do not call PM runtime functions in tb_retimer_scan()

We cannot call PM runtime functions in tb_retimer_scan() because it will
also be called when retimers are scanned from userspace (happens when
there is no device connected on ChromeOS for instance) and at the same
USB4 port runtime resume hook. This leads to hang because neither can
proceed.

Fix this by runtime resuming USB4 ports in tb_scan_port() instead. This
makes sure the ports are runtime PM active when retimers are added under
it while avoiding the reported hang as well.

Reported-by: Utkarsh Patel <utkarsh.h.patel@intel.com>
Fixes: 1e56c88a ("thunderbolt: Runtime resume USB4 port when retimers are scanned")
Cc: stable@vger.kernel.org
Acked-by: Yehezkel Bernat <YehezkelShB@gmail.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>