s390/topology: use for_each_set_bit to simplify the code

Use for_each_set_bit() to simplify the code.

spatch with a semantic match is used to found this.
(http://coccinelle.lip6.fr/)
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/topology.c

@@ -73,10 +73,7 @@ static struct mask_info *add_cpus_to_mask(struct topology_cpu *tl_cpu,
 {
 	unsigned int cpu;
 
-	for (cpu = find_first_bit(&tl_cpu->mask[0], TOPOLOGY_CPU_BITS);
-	     cpu < TOPOLOGY_CPU_BITS;
-	     cpu = find_next_bit(&tl_cpu->mask[0], TOPOLOGY_CPU_BITS, cpu + 1))
-	{
+	for_each_set_bit(cpu, &tl_cpu->mask[0], TOPOLOGY_CPU_BITS) {
 		unsigned int rcpu;
 		int lcpu;