Btrfs: remove unused ftrace include

Signed-off-by: jim owens <jowens@hp.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/async-thread.c

@@ -20,7 +20,6 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/freezer.h>
-#include <linux/ftrace.h>
 #include "async-thread.h"
 
 #define WORK_QUEUED_BIT 0

fs/btrfs/delayed-ref.c

@@ -18,7 +18,6 @@
 
 #include <linux/sched.h>
 #include <linux/sort.h>
-#include <linux/ftrace.h>
 #include "ctree.h"
 #include "delayed-ref.h"
 #include "transaction.h"