Implement ->read_iter for all proc "seq files" so that splice works on
them.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 static const struct proc_ops proc_seq_ops = {
        /* not permanent -- can call into arbitrary seq_operations */
        .proc_open      = proc_seq_open,
-       .proc_read      = seq_read,
+       .proc_read_iter = seq_read_iter,
        .proc_lseek     = seq_lseek,
        .proc_release   = proc_seq_release,
 };