direct-io: eliminate the offset argument to ->direct_IO

Including blkdev_direct_IO and dax_do_io.  It has to be ki_pos to actually
work, so eliminate the superflous argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c
index 49e1bd0..9dc4c6d 100644
--- a/fs/exofs/inode.c
+++ b/fs/exofs/inode.c
@@ -960,8 +960,7 @@
 
 
  /* TODO: Should be easy enough to do proprly */
-static ssize_t exofs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
-			       loff_t offset)
+static ssize_t exofs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 {
 	return 0;
 }