tracing: Make tracepoint_print_iter static

After change in commit 42391745 ("tracing: Make tracepoint_printk a
static_key"), this symbol is not used outside of the file, so mark it
static.

Link: https://lkml.kernel.org/r/20221122091456.72055-1-xiujianfeng@huawei.comSigned-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -85,7 +85,7 @@ void __init disable_tracing_selftest(const char *reason)
 #endif
 
 /* Pipe tracepoints to printk */
-struct trace_iterator *tracepoint_print_iter;
+static struct trace_iterator *tracepoint_print_iter;
 int tracepoint_printk;
 static bool tracepoint_printk_stop_on_boot __initdata;
 static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key);

kernel/trace/trace.h

@@ -1942,8 +1942,6 @@ static inline void tracer_hardirqs_on(unsigned long a0, unsigned long a1) { }
 static inline void tracer_hardirqs_off(unsigned long a0, unsigned long a1) { }
 #endif
 
-extern struct trace_iterator *tracepoint_print_iter;
-
 /*
  * Reset the state of the trace_iterator so that it can read consumed data.
  * Normally, the trace_iterator is used for reading the data when it is not