openrisc: Use of_get_cpu_hwid()

Replace open coded parsing of CPU nodes' 'reg' property with
of_get_cpu_hwid().

Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Cc: openrisc@lists.librecores.org
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Stafford Horne <shorne@gmail.com>
Link: https://lore.kernel.org/r/20211006164332.1981454-7-robh@kernel.org

arch/openrisc/kernel/smp.c

@@ -65,11 +65,7 @@ void __init smp_init_cpus(void)
 	u32 cpu_id;
 
 	for_each_of_cpu_node(cpu) {
-		if (of_property_read_u32(cpu, "reg", &cpu_id)) {
-			pr_warn("%s missing reg property", cpu->full_name);
-			continue;
-		}
-
+		cpu_id = of_get_cpu_hwid(cpu, 0);
 		if (cpu_id < NR_CPUS)
 			set_cpu_possible(cpu_id, true);
 	}