[IPV6]: small fix for ipv6_dev_get_saddr(...)

The "score.rule++" doesn't make any sense for me. 
According to codes above, I think it should be "hiscore.rule++;" .

Signed-off-by: Yan <Zheng&lt;yanzheng@21cn.com>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>