greybus: interface: implement unipro link hibernate call

Adds AP implementation of unipro link hibernation set power mode call
needed for proper cport closure and interface suspend and power off
transition.
Signed-off-by: David Lin <dtwlin@google.com>
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Alex Elder <elder@linaro.org>

drivers/staging/greybus/interface.c

@@ -641,11 +641,9 @@ static int gb_interface_activate_operation(struct gb_interface *intf)
 
 static int gb_interface_hibernate_link(struct gb_interface *intf)
 {
-	dev_dbg(&intf->dev, "%s\n", __func__);
-
-	/* FIXME: implement */
+	struct gb_svc *svc = intf->hd->svc;
 
-	return 0;
+	return gb_svc_intf_set_power_mode_hibernate(svc, intf->interface_id);
 }
 
 /*