[IPV6]: Fix return type for snmp6_free_dev()

This call is essentially void.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -283,12 +283,11 @@ static int snmp6_alloc_dev(struct inet6_dev *idev)
 	return err;
 }
 
-static int snmp6_free_dev(struct inet6_dev *idev)
+static void snmp6_free_dev(struct inet6_dev *idev)
 {
 	snmp_mib_free((void **)idev->stats.icmpv6msg);
 	snmp_mib_free((void **)idev->stats.icmpv6);
 	snmp_mib_free((void **)idev->stats.ipv6);
-	return 0;
 }
 
 /* Nobody refers to this device, we may destroy it. */