Fix a string format bug in qemu_cgroup.c

Signed-off-by: NTang Chen <tangchen@cn.fujitsu.com>
(cherry picked from commit 097da1ab)

src/qemu/qemu_cgroup.c

@@ -464,8 +464,8 @@ cleanup:
         rc = virCgroupSetCpuCfsPeriod(cgroup, old_period);
         if (rc < 0)
             virReportSystemError(-rc,
-                                 _("%s"),
-                                 "Unable to rollback cpu bandwidth period");
+                                 "%s",
+                                 _("Unable to rollback cpu bandwidth period"));
     }
 
     return -1;