soreuseport: Resolve merge conflict for v4/v6 ordering fix

soreuseport: Resolve merge conflict for v4/v6 ordering fix

0b1db8b5e48e ("soreuseport: fix ordering for mixed v4/v6 sockets")
was merged as a bug fix to the net tree.  Two conflicting changes
were committed to net-next before the above fix was merged back to
net-next:
78f1e7e98c8e ("udp: no longer use SLAB_DESTROY_BY_RCU")
67917ed40d3a ("tcp/dccp: do not touch listener sk_refcnt under synflood")

These changes switched the datastructure used for TCP and UDP sockets
from hlist_nulls to hlist.  This patch applies the necessary parts
of the net tree fix to net-next which were not automatic as part of the
merge.

Fixes: ad8cd4568cac ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net")
Signed-off-by: Craig Gallek <kraig@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>