ext4: move headers out of include/linux

Move ext4 headers out of include/linux.  This is just the trivial move,
there's some more thing that could be done later. 

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index 420554f8..d37ea67 100644
--- a/fs/ext4/bitmap.c
+++ b/fs/ext4/bitmap.c
@@ -9,7 +9,7 @@
 
 #include <linux/buffer_head.h>
 #include <linux/jbd2.h>
-#include <linux/ext4_fs.h>
+#include "ext4.h"
 
 #ifdef EXT4FS_DEBUG