drm/amdgpu/dm/mst: Use ->atomic_best_encoder

We are supposed to be atomic after all. We'll need this in a moment for
the next commit.

Acked-by: Alex Deucher <[e-mail]>
Reviewed-by: Harry Wentland <[e-mail]>
Signed-off-by: Lyude Paul <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 	return ret;
 }
 
-static struct drm_encoder *dm_mst_best_encoder(struct drm_connector *connector)
+static struct drm_encoder *
+dm_mst_atomic_best_encoder(struct drm_connector *connector,
+			   struct drm_connector_state *connector_state)
 {
-	struct amdgpu_dm_connector *amdgpu_dm_connector = to_amdgpu_dm_connector(connector);
-
-	return &amdgpu_dm_connector->mst_encoder->base;
+	return &to_amdgpu_dm_connector(connector)->mst_encoder->base;
 }
 
 static const struct drm_connector_helper_funcs dm_dp_mst_connector_helper_funcs = {
 	.get_modes = dm_dp_mst_get_modes,
 	.mode_valid = amdgpu_dm_connector_mode_valid,
-	.best_encoder = dm_mst_best_encoder,
+	.atomic_best_encoder = dm_mst_atomic_best_encoder,
 };
 
 static void amdgpu_dm_encoder_destroy(struct drm_encoder *encoder)