constify dentry_operations: rest

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/pipe.c b/fs/pipe.c
index df37195..6ddf052 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -870,7 +870,7 @@
 				dentry->d_inode->i_ino);
 }
 
-static struct dentry_operations pipefs_dentry_operations = {
+static const struct dentry_operations pipefs_dentry_operations = {
 	.d_delete	= pipefs_delete_dentry,
 	.d_dname	= pipefs_dname,
 };