thunderbolt: Improve multi-display DisplayPort tunnel allocation

thunderbolt: Improve multi-display DisplayPort tunnel allocation

When 3 monitors are connected through Thunderbolt dock to the system at
once, one of the monitors might fail to establish DisplayPort tunnel.
This happens during DP bandwidth negotiation - each monitor takes
maximum bandwidth that is supported and there might not be enough for
3rd display. In this case Thunderbolt driver drops DP tunnel and
'forgets' about it but with DP bandwidth allocation mode, that comes in
later, some bandwidth might be freed.

Make Thunderbolt driver check again if DP tunnel can be established
after DP bandwidth consumption changed.

Signed-off-by: Alan Borzeszkowski <alan.borzeszkowski@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>