app/testpmd: add tunnel types

app/testpmd: add tunnel types

Current testpmd implementation supports VXLAN only for tunnel offload.
Add GRE, NVGRE and GENEVE for tunnel offload flow matches.

For example:
testpmd> flow tunnel create 0 type vxlan
port 0: flow tunnel #1 type vxlan
testpmd> flow tunnel create 0 type nvgre
port 0: flow tunnel #2 type nvgre
testpmd> flow tunnel create 0 type gre
port 0: flow tunnel #3 type gre
testpmd> flow tunnel create 0 type geneve
port 0: flow tunnel #4 type geneve

Fixes: 1b9f274623b8 ("app/testpmd: add commands for tunnel offload")
Cc: stable@dpdk.org
Signed-off-by: Eli Britstein <elibr@nvidia.com>
Reviewed-by: Gregory Etelson <getelson@nvidia.com>