net: openvswitch: suitable access to the dp_meters

To fix the following sparse warning:
| net/openvswitch/meter.c:109:38: sparse: sparse: incorrect type
| in assignment (different address spaces) ...
| net/openvswitch/meter.c:720:45: sparse: sparse: incorrect type
| in argument 1 (different address spaces) ...

Reported-by: kbuild test robot <[e-mail]>
Signed-off-by: Tonghao Zhang <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/openvswitch/meter.c

···
 		return -ENOMEM;
 
 	for (i = 0; i < n_meters; i++)
-		new_ti->dp_meters[i] =
-			rcu_dereference_ovsl(ti->dp_meters[i]);
+		if (rcu_dereference_ovsl(ti->dp_meters[i]))
+			new_ti->dp_meters[i] = ti->dp_meters[i];
 
 	rcu_assign_pointer(tbl->ti, new_ti);
 	call_rcu(&ti->rcu, dp_meter_instance_free_rcu);
···
 	int i;
 
 	for (i = 0; i < ti->n_meters; i++)
-		ovs_meter_free(ti->dp_meters[i]);
+		ovs_meter_free(rcu_dereference_raw(ti->dp_meters[i]));
 
 	dp_meter_instance_free(ti);
 }