s2io: set_multicast_list bug

The mac_addr variable doesn't get reset between
(re)additions of multicast addresses. One byte
of all multicast addresses (except the first)
can be incorrect.
Signed-off-by: NArthur Kepner <akepner@sgi.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

drivers/net/s2io.c

@@ -4092,6 +4092,7 @@ static void s2io_set_multicast(struct net_device *dev)
 		     i++, mclist = mclist->next) {
 			memcpy(sp->usr_addrs[i].addr, mclist->dmi_addr,
 			       ETH_ALEN);
+			mac_addr = 0;
 			for (j = 0; j < ETH_ALEN; j++) {
 				mac_addr |= mclist->dmi_addr[j];
 				mac_addr <<= 8;