net: http: Connection close fix if old connection is active

If we receive a HTTP request and if the earlier context is still
active and it is not the same as the new one, then close the earlier
one. Otherwise it is possible that the old context will be left into
TCP ESTABLISHED state and would never be released. Example of this
is that we had IPv4 connection active and then IPv6 connection is
established, in this case we will disconnect the IPv4 connection
after this commit.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>