mm: mark most vm_operations_struct const

With two exceptions (drm/qxl and drm/radeon) all vm_operations_struct
structs should be constant.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
index 26a46f4..b160c0c 100644
--- a/arch/x86/entry/vsyscall/vsyscall_64.c
+++ b/arch/x86/entry/vsyscall/vsyscall_64.c
@@ -277,7 +277,7 @@
 {
 	return "[vsyscall]";
 }
-static struct vm_operations_struct gate_vma_ops = {
+static const struct vm_operations_struct gate_vma_ops = {
 	.name = gate_vma_name,
 };
 static struct vm_area_struct gate_vma = {