drm/amd/display: Properly reuse completion structure

[Why]
Connecting displays to TBT3 docks often produces invalid
replies for DPIA AUX requests. It turns out the completion
structure was not re-initialized before reusing it, resulting
in immature wake up to completion.

[How]
Properly call reinit_completion() on reused completion structure.

Cc: stable@vger.kernel.org
Reviewed-by: Solomon Chiu <solomon.chiu@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Stylon Wang <stylon.wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -10514,6 +10514,7 @@ int amdgpu_dm_process_dmub_aux_transfer_sync(
 	ret = p_notify->aux_reply.length;
 	*operation_result = p_notify->result;
 out:
+	reinit_completion(&adev->dm.dmub_aux_transfer_done);
 	mutex_unlock(&adev->dm.dpia_aux_lock);
 	return ret;
 }
@@ -10541,6 +10542,8 @@ int amdgpu_dm_process_dmub_set_config_sync(
 		*operation_result = SET_CONFIG_UNKNOWN_ERROR;
 	}
 
+	if (!is_cmd_complete)
+		reinit_completion(&adev->dm.dmub_aux_transfer_done);
 	mutex_unlock(&adev->dm.dpia_aux_lock);
 	return ret;
 }