selftests: net: more strict check in net_helper

selftests: net: more strict check in net_helper

The helper waiting for a listener port can match any socket whose
hexadecimal representation of source or destination addresses
matches that of the given port.

Additionally, any socket state is accepted.

All the above can let the helper return successfully before the
relevant listener is actually ready, with unexpected results.

So far I could not find any related failure in the netdev CI, but
the next patch is going to make the critical event more easily
reproducible.

Address the issue matching the port hex only vs the relevant socket
field and additionally checking the socket state for TCP sockets.

Fixes: 3bdd9fd29cb0 ("selftests/net: synchronize udpgro tests' tx and rx connection")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/192b3dbc443d953be32991d1b0ca432bd4c65008.1707731086.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>