thunderbolt: Scan retimers after device router has been enumerated

Thomas reported connection issues on AMD system with Pluggable UD-4VPD
dock. After some experiments it looks like the device has some sort of
internal timeout that triggers reconnect. This is completely against the
USB4 spec, as there is no requirement for the host to enumerate the
device right away or even at all.

In Linux case the delay is caused by scanning of retimers on the link so
we can work this around by doing the scanning after the device router
has been enumerated.

Reported-by: Thomas Lynema <lyz27@yahoo.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219748


Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>