selftests/net: add missing tests to Makefile

Find some tests are missed in Makefile by running:
for file in $(ls *.sh); do grep -q $file Makefile || echo $file; done

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>