tracing: Fix #if CONFIG_MODULES to #ifdef CONFIG_MODULES

A typo was introduced when adding the ":mod:" command that did
a "#if CONFIG_MODULES" instead of a "#ifdef CONFIG_MODULES".
Fix it.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/20250120125745.4ac90ca6@gandalf.local.home
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501190121.E2CIJuUj-lkp@intel.com/
Fixes: b355247 ("tracing: Cache ":mod:" events for modules not loaded yet")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: rostedt

kernel/trace/trace_events.c

@@ -857,7 +857,7 @@ static int ftrace_event_enable_disable(struct trace_event_file *file,
 	return __ftrace_event_enable_disable(file, enable, 0);
 }
 
-#if CONFIG_MODULES
+#ifdef CONFIG_MODULES
 struct event_mod_load {
 	struct list_head	list;
 	char			*module;