qemu: Add missing goto error in qemuRestoreCgroupState

Commit af2a1f05 tried clearly separating each condition in
qemuRestoreCgroupState() for the sake of readability, however somehow
one condition body was missing.  That means that the body of the next
condition got executed only if both of there were true, which is
impossible, thus resulting in a dead code and a logic error.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/qemu/qemu_cgroup.c

@@ -800,9 +800,7 @@ qemuRestoreCgroupState(virDomainObjPtr vm)
         goto error;
 
     if ((empty = virCgroupHasEmptyTasks(priv->cgroup,
-                                        VIR_CGROUP_CONTROLLER_CPUSET)) < 0)
-
-    if (!empty)
+                                        VIR_CGROUP_CONTROLLER_CPUSET)) <= 0)
         goto error;
 
     if (virCgroupSetCpusetMems(priv->cgroup, mem_mask) < 0)