qemu: processBlockJob: Don't unlock @vm twice

Commit 1a92c719 moved code to handle block job events to a different
function that is executed in a separate thread. The caller of
processBlockJob handles locking and unlocking of @vm, so the we should
not do it in the function itself.

src/qemu/qemu_driver.c

@@ -4574,7 +4574,6 @@ processBlockJobEvent(virQEMUDriverPtr driver,
             VIR_WARN("Unable to update persistent definition on vm %s "
                      "after block job", vm->def->name);
     }
-    virObjectUnlock(vm);
     virObjectUnref(cfg);
 
     if (event)