tracing: toplevel d_entry already initialized

Currently we have following call flow:

    tracer_init_tracefs()
        tracing_init_dentry()
        event_trace_init()
            tracing_init_dentry()

This shows tracing_init_dentry() is called twice in this flow and this
is not necessary.

Let's remove the second one when it is for sure be properly initialized.

Link: https://lkml.kernel.org/r/20200712011036.70948-4-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_events.c

@@ -3434,7 +3434,6 @@ early_initcall(event_trace_enable_again);
 __init int event_trace_init(void)
 {
 	struct trace_array *tr;
-	struct dentry *d_tracer;
 	struct dentry *entry;
 	int ret;
 
@@ -3442,11 +3441,7 @@ __init int event_trace_init(void)
 	if (!tr)
 		return -ENODEV;
 
-	d_tracer = tracing_init_dentry();
-	if (IS_ERR(d_tracer))
-		return 0;
-
-	entry = tracefs_create_file("available_events", 0444, d_tracer,
+	entry = tracefs_create_file("available_events", 0444, NULL,
 				    tr, &ftrace_avail_fops);
 	if (!entry)
 		pr_warn("Could not create tracefs 'available_events' entry\n");
@@ -3457,7 +3452,7 @@ __init int event_trace_init(void)
 	if (trace_define_common_fields())
 		pr_warn("tracing: Failed to allocate common fields");
 
-	ret = early_event_add_tracer(d_tracer, tr);
+	ret = early_event_add_tracer(NULL, tr);
 	if (ret)
 		return ret;