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/fuse/file.c b/fs/fuse/file.c
index c1a67da..3d355e9 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2782,8 +2782,7 @@
 }
 
 static ssize_t
-fuse_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
-			loff_t offset)
+fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	ssize_t ret = 0;