nfp: flower: add support for tunnel offload without key ID

nfp: flower: add support for tunnel offload without key ID

Currently nfp driver will reject to offload tunnel key action without
tunnel key ID which means tunnel ID is 0. But it is a normal case for tc
flower since user can setup a tunnel with tunnel ID is 0.

So we need to support this case to accept tunnel key action without
tunnel key ID.

Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com>
Reviewed-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20220729091641.354748-1-simon.horman@corigine.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>