ams: globally prefer R_RETURN to return for ams::Result

stratosphere/ams_mitm/source/sysupdater/sysupdater_async_impl.cpp

@@ -70,7 +70,7 @@ namespace ams::mitm::sysupdater {
     }
 
     Result AsyncPrepareSdCardUpdateImpl::Execute() {
-        return m_task->PrepareAndExecute();
+        R_RETURN(m_task->PrepareAndExecute());
     }
 
     void AsyncPrepareSdCardUpdateImpl::CancelImpl() {