Commit da12c90e
"netlink: Add compare function for netlink_table"
only set compare at the time we create kernel netlink,
and reset compare to NULL at the time we finially
release netlink socket, but netlink_lookup wants
the compare exist always.

So we should set compare after we allocate nl_table,
and never reset it. make comapre exist all the time.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NGao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>