proc/stat: switch to ->read_iter

Implement ->read_iter so that splice can be used on this file.
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>

fs/proc/stat.c

@@ -226,7 +226,7 @@ static int stat_open(struct inode *inode, struct file *file)
 static const struct proc_ops stat_proc_ops = {
 	.proc_flags	= PROC_ENTRY_PERMANENT,
 	.proc_open	= stat_open,
-	.proc_read	= seq_read,
+	.proc_read_iter	= seq_read_iter,
 	.proc_lseek	= seq_lseek,
 	.proc_release	= single_release,
 };