thunderbolt: Wait for the lanes to actually bond

It may take some time until the two lanes enter bonded state so poll for
the link width to match what is expected before going forward. This ensures
the link is in expected state before we start establishing paths through
it.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Change-Id: I835fe02fe439448c8302e4643fe57706806a35b3