drm/amd/display: Fix active dongle hotplug

Clean fake sink flag after detecting link on downstream port.
Fixing display light-up after  "hot-unplug&plug again" downstream
of an active dongle.

Signed-off-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1037,6 +1037,10 @@ static void handle_hpd_rx_irq(void *param)
 			!is_mst_root_connector) {
 		/* Downstream Port status changed. */
 		if (dc_link_detect(dc_link, DETECT_REASON_HPDRX)) {
+
+			if (aconnector->fake_enable)
+				aconnector->fake_enable = false;
+
 			amdgpu_dm_update_connector_after_detect(aconnector);