const: mark struct vm_struct_operations

* mark struct vm_area_struct::vm_ops as const
* mark vm_ops in AGP code

But leave TTM code alone, something is fishy there with global vm_ops
being used.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/ramfs.h b/include/linux/ramfs.h
index 37aaf2b..4e768dd 100644
--- a/include/linux/ramfs.h
+++ b/include/linux/ramfs.h
@@ -17,7 +17,7 @@
 #endif
 
 extern const struct file_operations ramfs_file_operations;
-extern struct vm_operations_struct generic_file_vm_ops;
+extern const struct vm_operations_struct generic_file_vm_ops;
 extern int __init init_rootfs(void);
 
 #endif