app/testpmd: fix flow rule with flex input link

app/testpmd: fix flow rule with flex input link

Testpmd reads flex item configuration from a JSON file.
Flex item input link description is stored in testpmd
flow item format. For example, `eth type is 0x0800`.
The item description is placed into a general testpmd CLI
flow rule command template and parsed to convert string into
flow item object.

The patch adds the `actions` section to the flow rule template.

Fixes: 59f3a8acbcdb ("app/testpmd: add flex item commands")
Cc: stable@dpdk.org
Signed-off-by: Gregory Etelson <getelson@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>