test: perf: l2fwd detect missing odp_generator
test: perf: l2fwd detect missing odp_generator

The script did not check that the odp_generator was present.
Updates to ensure the clean up is always called at EXIT

Signed-off-by: Mike Holmes <ed44c09f4d7f698f5510adc894a872c73e08c8bd@linaro.org>
Reviewed-by: Stuart Haslam <1fce01f364ef5298e64e07a42e08efeef153fa98@linaro.org>
Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>

mike-holmes-linaro/odp,nmorey/odp,rsalveti/odp,ravineet-singh/odp,mike-holmes-linaro/odp,rsalveti/odp,rsalveti/odp,dkrot/odp,erachmi/odp,ravineet-singh/odp,nmorey/odp,nmorey/odp,erachmi/odp,erachmi/odp,rsalveti/odp,dkrot/odp,dkrot/odp,erachmi/odp,mike-holmes-linaro/odp,dkrot/odp,nmorey/odp,rsalveti/odp,mike-holmes-linaro/odp,ravineet-singh/odp,ravineet-singh/odp