net: Replace deprecated CPU-hotplug functions.

The functions get_online_cpus() and put_online_cpus() have been
deprecated during the CPU hotplug rework. They map directly to
cpus_read_lock() and cpus_read_unlock().

Replace deprecated CPU-hotplug functions with the official version.
The behavior remains unchanged.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/dev.c

@@ -5797,7 +5797,7 @@ static void flush_all_backlogs(void)
 	 */
 	ASSERT_RTNL();
 
-	get_online_cpus();
+	cpus_read_lock();
 
 	cpumask_clear(&flush_cpus);
 	for_each_online_cpu(cpu) {
@@ -5815,7 +5815,7 @@ static void flush_all_backlogs(void)
 	for_each_cpu(cpu, &flush_cpus)
 		flush_work(per_cpu_ptr(&flush_works, cpu));
 
-	put_online_cpus();
+	cpus_read_unlock();
 }
 
 /* Pass the currently batched GRO_NORMAL SKBs up to the stack. */