const: constify remaining pipe_buf_operations

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/relay.c b/kernel/relay.c
index 760c262..c705a41 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -1198,7 +1198,7 @@
 	relay_consume_bytes(rbuf, buf->private);
 }
 
-static struct pipe_buf_operations relay_pipe_buf_ops = {
+static const struct pipe_buf_operations relay_pipe_buf_ops = {
 	.can_merge = 0,
 	.map = generic_pipe_buf_map,
 	.unmap = generic_pipe_buf_unmap,