app/testpmd: fix flow tunnel commands

testpmd provides commands to test tunnel offload rte_flow
capabilities. Testpmd tunnel commands allow to configure new ofloaded
tunnel types, list existing offloaded tunnels and destroy existing
offloaded tunnels.
Tunnel offload commands allowed parameters repetition. For example,
the following commands were accepted:
testpmd> flow tunnel create 0 create 1 type vxlan
or
testpmd> flow tunnel list 0 list 1

Current patch fixed that fault. Correct tunnel commands syntax is:
testpmd> flow tunnel create <port> type <tunnel type>
testpmd> flow tunnel list <port>
testpmd> flow tunnel destroy <port> id <tunnel id>

Fixes: 1b9f274623b8 ("app/testpmd: add commands for tunnel offload")

Signed-off-by: Gregory Etelson <getelson@nvidia.com>
Acked-by: Ori Kam <orika@nvidia.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>