selftests/bpf: use localhost in tcp_{server,client}.py

Bind and connect to localhost. There is no reason for this test to
use non-localhost interface. This lets us run this test in a network
namespace.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/tcp_client.py

@@ -30,12 +30,11 @@ def send(sock, s):
 
 
 serverPort = int(sys.argv[1])
-HostName = socket.gethostname()
 
 # create active socket
 sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
 try:
-    sock.connect((HostName, serverPort))
+    sock.connect(('localhost', serverPort))
 except socket.error as e:
     sys.exit(1)