vpp_device: updates for 1n-tx2 testbeds

One ThunderX2 9975 server (.69) was replaced with two ThunderX2 9980
(.70, .71) servers. Move the .69 server under ansible perf section in
anticipation of repurposing it for that purpose. Update the ansible
scripts with .70 and .71 config and rename port names in device.sh lib
to reflect the NIC differences between .69 and .70 (and .71).

Change-Id: I88b75648735243e5559175d3192ffcc8fc70071c
Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>