selftests: net: add more missing kernel config

The reuseport_addr_any.sh is currently skipping DCCP tests and
pmtu.sh is skipping all the FOU/GUE related cases: add the missing
options.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/38d3ca7f909736c1aef56e6244d67c82a9bba6ff.1707326987.git.pabeni@redhat.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>