tc-testing: add geneve options in tunnel_key unit tests

Extend tc tunnel_key action unit tests with geneve options. Tests
include testing single and multiple geneve options, as well as
testing geneve options that are expected to fail.

Signed-off-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Acked-by: Lucas Bates <lucasb@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>