UAPI Changes: None

Cross-subsystem Changes: None

Core Changes: Fixed regressions introduced by commit cd82d82cbc04
("drm/dp_mst: Add branch bandwidth validation to MST atomic check"),
which would cause us to:

* Calculate the available bandwidth on an MST topology incorrectly, and
  as a result reject most display configurations that would try to enable
  more then one sink on a topology
* Occasionally expose MST connectors to userspace before finishing
  probing their PBN capabilities, resulting in us rejecting display
  configurations because we assumed briefly that no bandwidth was
  available

Driver Changes: None