net/core: __hw_addr_create_ex does not initialize sync_cnt

The sync_cnt field is not being initialized, which can result
in arbitrary values in the field.  Fixed by initializing it to zero.
Signed-off-by: NJay Vosburgh <fubar@us.ibm.com>
Reviewed-by: NVlad Yasevich <vyasevic@redhat.com>
Tested-by: NShawn Bohrer <sbohrer@rgmadvisors.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/dev_addr_lists.c

@@ -39,6 +39,7 @@ static int __hw_addr_create_ex(struct netdev_hw_addr_list *list,
 	ha->refcount = 1;
 	ha->global_use = global;
 	ha->synced = sync;
+	ha->sync_cnt = 0;
 	list_add_tail_rcu(&ha->list, &list->list);
 	list->count++;