nfs: switch to ->read_iter()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index dd8bfc2..e598e4a 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -320,7 +320,7 @@
 int nfs_file_fsync_commit(struct file *, loff_t, loff_t, int);
 loff_t nfs_file_llseek(struct file *, loff_t, int);
 int nfs_file_flush(struct file *, fl_owner_t);
-ssize_t nfs_file_read(struct kiocb *, const struct iovec *, unsigned long, loff_t);
+ssize_t nfs_file_read(struct kiocb *, struct iov_iter *);
 ssize_t nfs_file_splice_read(struct file *, loff_t *, struct pipe_inode_info *,
 			     size_t, unsigned int);
 int nfs_file_mmap(struct file *, struct vm_area_struct *);