IB/rxe: Constify static rxe_vm_ops

Constify static rxe_vm_ops that is never modified.
Signed-off-by: Kamal Heib <kamalh@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rxe/rxe_mmap.c

@@ -76,7 +76,7 @@ static void rxe_vma_close(struct vm_area_struct *vma)
 	kref_put(&ip->ref, rxe_mmap_release);
 }
 
-static struct vm_operations_struct rxe_vm_ops = {
+static const struct vm_operations_struct rxe_vm_ops = {
 	.open = rxe_vma_open,
 	.close = rxe_vma_close,
 };