cpumask: convert kernel trace functions further

Impact: Reduce future memory usage, use new cpumask API.

Since the last patch was created and acked, more old cpumask users
slipped into kernel/trace.

Mostly trivial conversions, except struct trace_iterator's "started"
member becomes a cpumask_var_t.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

kernel/trace/trace_power.c

@@ -39,7 +39,7 @@ static int power_trace_init(struct trace_array *tr)
 
 	trace_power_enabled = 1;
 
-	for_each_cpu_mask(cpu, cpu_possible_map)
+	for_each_cpu(cpu, cpu_possible_mask)
 		tracing_reset(tr, cpu);
 	return 0;
 }