dm table: Constify static struct blk_ksm_ll_ops

The only usage of dm_ksm_ll_ops is to make a copy of it to the ksm_ll_ops
field in the blk_keyslot_manager struct. Make it const to allow the
compiler to put it in read-only memory.
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-table.c

@@ -1244,7 +1244,7 @@ static int dm_keyslot_evict(struct blk_keyslot_manager *ksm,
 	return args.err;
 }
 
-static struct blk_ksm_ll_ops dm_ksm_ll_ops = {
+static const struct blk_ksm_ll_ops dm_ksm_ll_ops = {
 	.keyslot_evict = dm_keyslot_evict,
 };