integration: Tunneling protocols support update

integration: Tunneling protocols support update

Support of tunneling protocols by IxNet was limited to OP2P and PTUNP
deployment scenarios. This patch adds generic support for generation
of VXLAN, GRE and GENEVE frames by IxNet into integration testcases.

As part of this patch, the processing of tunnel type settings was
modified to follow VSPERF priority order during configuration parameter
evaluation.

JIRA: VSPERF-573

Change-Id: I7bf7d4a5545a6b130cc3ac252efaabe4b97bdb29
Signed-off-by: Martin Klozik <martin.klozik@tieto.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Christian Trautman <ctrautma@redhat.com>
Reviewed-by: Sridhar Rao <sridhar.rao@spirent.com>
Reviewed-by: Cian Ferriter <cian.ferriter@intel.com>
Reviewed-by: Richard Elias <richard.elias@tieto.com>