powerpc/pseries: Add missing of_node_put()s in hotplug-cpu.c

In pseries_cpuhp_cache_use_count() and pseries_cpuhp_detach_nodes(),
we need carefully hold the reference returned by
of_find_next_cache_node() and use it to call of_node_put() to keep
refcount balance.
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220621111701.4082889-1-windhl@126.com

arch/powerpc/platforms/pseries/hotplug-cpu.c

@@ -619,17 +619,21 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
 static unsigned int pseries_cpuhp_cache_use_count(const struct device_node *cachedn)
 {
 	unsigned int use_count = 0;
-	struct device_node *dn;
+	struct device_node *dn, *tn;
 
 	WARN_ON(!of_node_is_type(cachedn, "cache"));
 
 	for_each_of_cpu_node(dn) {
-		if (of_find_next_cache_node(dn) == cachedn)
+		tn = of_find_next_cache_node(dn);
+		of_node_put(tn);
+		if (tn == cachedn)
 			use_count++;
 	}
 
 	for_each_node_by_type(dn, "cache") {
-		if (of_find_next_cache_node(dn) == cachedn)
+		tn = of_find_next_cache_node(dn);
+		of_node_put(tn);
+		if (tn == cachedn)
 			use_count++;
 	}
 
@@ -649,10 +653,13 @@ static int pseries_cpuhp_detach_nodes(struct device_node *cpudn)
 
 	dn = cpudn;
 	while ((dn = of_find_next_cache_node(dn))) {
-		if (pseries_cpuhp_cache_use_count(dn) > 1)
+		if (pseries_cpuhp_cache_use_count(dn) > 1) {
+			of_node_put(dn);
 			break;
+		}
 
 		ret = of_changeset_detach_node(&cs, dn);
+		of_node_put(dn);
 		if (ret)
 			goto out;
 	}