drm/amd/display: fix trigger_hotplug to support mst case

[Why & How]
Correct few problems below to have debugfs trigger_hotplug entry
supports mst case

* Adjust the place for acquiring the hpd_lock. We'll also access
  dc_link when simulate unplug
* When detect the connector is a mst root, call
  reset_cur_dp_mst_topology() to simulate unplug
* Don't support hotplug caused by CSN message since we can't change
  mst topology info directly. We can't simulate that
* Clean up redundant code

Tested-by: Daniel Wheeler <[email protected]>
Reviewed-by: Hersen Wu <[email protected]>
Acked-by: Alan Liu <[email protected]>
Signed-off-by: Wayne Lin <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

0 files changed, 0 insertions, 0 deletions