cgroup: Use kvfree in pidlist_free()

The wrapper already calls the appropriate free
function, use it instead of spinning our own.
Signed-off-by: Bandan Das <bsd@redhat.com>
Acked-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

kernel/cgroup.c

@@ -3806,10 +3806,7 @@ static void *pidlist_allocate(int count)
 
 static void pidlist_free(void *p)
 {
-	if (is_vmalloc_addr(p))
-		vfree(p);
-	else
-		kfree(p);
+	kvfree(p);
 }
 
 /*