try disable memory downgrade on running VMs

app/UI/VmUpdate/Sections/Qemu/GeneralSection.php

@@ -131,7 +131,7 @@ class GeneralSection extends BaseSection
             __FUNCTION__,
             $vm->isRunning(),
             'Debug',
-            $vm->getMem()
+            $vm->getMemory()
         );
 
         $field = new Range('memory', $this->resourceManager->memory()->getMin(), $this->resourceManager->memory()->free());