tracing/osnoise: Use for_each_online_cpu() instead of for_each_cpu()

Replace the opencoded for_each_cpu(cpu, cpu_online_mask) loop with the
more readable and equivalent for_each_online_cpu(cpu) macro.

Link: https://lore.kernel.org/20250811064158.2456-1-wangfushuai@baidu.com
Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: Fushuai Wang

kernel/trace/trace_osnoise.c

@@ -271,7 +271,7 @@ static inline void tlat_var_reset(void)
 	 * So far, all the values are initialized as 0, so
 	 * zeroing the structure is perfect.
 	 */
-	for_each_cpu(cpu, cpu_online_mask) {
+	for_each_online_cpu(cpu) {
 		tlat_var = per_cpu_ptr(&per_cpu_timerlat_var, cpu);
 		if (tlat_var->kthread)
 			hrtimer_cancel(&tlat_var->timer);
@@ -295,7 +295,7 @@ static inline void osn_var_reset(void)
 	 * So far, all the values are initialized as 0, so
 	 * zeroing the structure is perfect.
 	 */
-	for_each_cpu(cpu, cpu_online_mask) {
+	for_each_online_cpu(cpu) {
 		osn_var = per_cpu_ptr(&per_cpu_osnoise_var, cpu);
 		memset(osn_var, 0, sizeof(*osn_var));
 	}