thunderbolt: Add DP OUT resource when DP tunnel is discovered

If the boot firmware implements a connection manager of its own it may
create a DisplayPort tunnel and will be handed off to Linux connection
manager, but the DP OUT resource is not saved in the dp_resource list.

This patch adds tunnelled DP OUT port to the dp_resource list once the
DP tunnel is discovered.

Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Tested-by: Renjith Pananchikkal <Renjith.Pananchikkal@amd.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>