powerpc/powermac/udbg_scc: Add missing of_node_put()s in udbg_scc_init()

During the iteration of for_each_child_of_node(), we need to call
of_node_put() for the old references stored in to 'ch_def' and 'ch_a'
as their refcounters have been increased in last iteration.
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220716074344.540049-1-windhl@126.com

arch/powerpc/platforms/powermac/udbg_scc.c

@@ -81,10 +81,14 @@ void __init udbg_scc_init(int force_scc)
 	if (path != NULL)
 		stdout = of_find_node_by_path(path);
 	for_each_child_of_node(escc, ch) {
-		if (ch == stdout)
+		if (ch == stdout) {
+			of_node_put(ch_def);
 			ch_def = of_node_get(ch);
-		if (of_node_name_eq(ch, "ch-a"))
+		}
+		if (of_node_name_eq(ch, "ch-a")) {
+			of_node_put(ch_a);
 			ch_a = of_node_get(ch);
+		}
 	}
 	if (ch_def == NULL && !force_scc)
 		goto bail;