direct_IO: remove rw from a_ops->direct_IO()

Now that no one is using rw, remove it completely.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
index 0085d52..75fd5d8 100644
--- a/fs/hfs/inode.c
+++ b/fs/hfs/inode.c
@@ -124,8 +124,8 @@
 	return res ? try_to_free_buffers(page) : 0;
 }
 
-static ssize_t hfs_direct_IO(int rw, struct kiocb *iocb,
-		struct iov_iter *iter, loff_t offset)
+static ssize_t hfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
+			     loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;