cgroup: convert all non-memcg controllers to the new cftype interface

Convert debug, freezer, cpuset, cpu_cgroup, cpuacct, net_prio, blkio,
net_cls and device controllers to use the new cftype based interface.
Termination entry is added to cftype arrays and populate callbacks are
replaced with cgroup_subsys->base_cftypes initializations.

This is functionally identical transformation.  There shouldn't be any
visible behavior change.

memcg is rather special and will be converted separately.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Vivek Goyal <vgoyal@redhat.com>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 66c1e3b..835ae29 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5349,19 +5349,15 @@
 		.name = "releasable",
 		.read_u64 = releasable_read,
 	},
-};
 
-static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
-{
-	return cgroup_add_files(cont, ss, debug_files,
-				ARRAY_SIZE(debug_files));
-}
+	{ }	/* terminate */
+};
 
 struct cgroup_subsys debug_subsys = {
 	.name = "debug",
 	.create = debug_create,
 	.destroy = debug_destroy,
-	.populate = debug_populate,
 	.subsys_id = debug_subsys_id,
+	.base_cftypes = debug_files,
 };
 #endif /* CONFIG_CGROUP_DEBUG */