tcp: Silence warning: ‘in6’ may be used uninitialized

tcp: Silence warning: ‘in6’ may be used uninitialized

Initialise in6 to avoid...

In file included from include/net/inetpeer.h:15:0,
                 from include/net/route.h:28,
                 from include/net/inet_hashtables.h:32,
                 from include/net/tcp.h:37,
                 from net/ipv4/tcp.c:275:
net/ipv4/tcp.c: In function ‘tcp_nuke_addr’:
include/net/ipv6.h:417:34: warning: ‘in6’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  return ((ul1[0] ^ ul2[0]) | (ul1[1] ^ ul2[1])) == 0UL;
                                  ^
net/ipv4/tcp.c:3513:19: note: ‘in6’ was declared here
  struct in6_addr *in6;

Signed-off-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>