tracing: Rename ftrace_event.h to trace_events.h

The term "ftrace" is really the infrastructure of the function hooks,
and not the trace events. Rename ftrace_event.h to trace_events.h to
represent the trace_event infrastructure and decouple the term ftrace
from it.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/mm/debug.c b/mm/debug.c
index 3eb3ac2..76089dd 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -7,7 +7,7 @@
 
 #include <linux/kernel.h>
 #include <linux/mm.h>
-#include <linux/ftrace_event.h>
+#include <linux/trace_events.h>
 #include <linux/memcontrol.h>
 
 static const struct trace_print_flags pageflag_names[] = {