BTRFS: Don't include disk-io.h twice in check-integrity.c

Once should be enough.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

fs/btrfs/check-integrity.c

@@ -89,7 +89,6 @@
 #include "disk-io.h"
 #include "transaction.h"
 #include "extent_io.h"
-#include "disk-io.h"
 #include "volumes.h"
 #include "print-tree.h"
 #include "locking.h"