thunderbolt: Check router generation before connecting xHCI

Only Thunderbolt 3 routers need the xHCI connection flow. This also
ensures the router actually has both lane adapters (1 and 3). While
there move declaration of the boolean variables inside the block where
they are being used.

Fixes: 30a4eca6 ("thunderbolt: Add internal xHCI connect flows for Thunderbolt 3 devices")
Cc: stable@vger.kernel.org
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>