vm: use the same testpmd sources inside VM

vm: use the same testpmd sources inside VM

Always copy testpmd sources from the directory with vHost User
version of DPDK. This will avoid possible issues with missing
dependencies in some VM images. It will also ensure, that testpmd
inside VM is agnostic to chosen vHost method.

Change-Id: I0496cc846eff3f7d4c1aef0a9c825545a4c3c818
JIRA: VSPERF-283
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Christian Trautman <ctrautma@redhat.com>
Reviewed-by: Brian Castelli <brian.castelli@spirent.com>