tracing: Simplify defining of the next event id

The value to be used and compared in trace_search_list() is "last + 1".
Let's just define next to be "last + 1" instead of doing the addition
each time.

Link: https://lkml.kernel.org/r/20200703020612.12930-2-richard.weiyang@linux.alibaba.comSigned-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace_output.c

@@ -675,11 +675,11 @@ static LIST_HEAD(ftrace_event_list);
 static int trace_search_list(struct list_head **list)
 {
 	struct trace_event *e;
-	int last = __TRACE_LAST_TYPE;
+	int next = __TRACE_LAST_TYPE + 1;
 
 	if (list_empty(&ftrace_event_list)) {
 		*list = &ftrace_event_list;
-		return last + 1;
+		return next;
 	}
 
 	/*
@@ -687,17 +687,17 @@ static int trace_search_list(struct list_head **list)
 	 * lets see if somebody freed one.
 	 */
 	list_for_each_entry(e, &ftrace_event_list, list) {
-		if (e->type != last + 1)
+		if (e->type != next)
 			break;
-		last++;
+		next++;
 	}
 
 	/* Did we used up all 65 thousand events??? */
-	if ((last + 1) > TRACE_EVENT_TYPE_MAX)
+	if (next > TRACE_EVENT_TYPE_MAX)
 		return 0;
 
 	*list = &e->list;
-	return last + 1;
+	return next;
 }
 
 void trace_event_read_lock(void)