vswitches: Remove datapath after stopping OVS

vswitches: Remove datapath after stopping OVS

Remove the datapath that OVS creates, ovs-system, (can be viewed by ip link)
after running OVS vanilla tests.

Change-Id: I087c7b3f5afa546258227939ffcb38f0192f0d98
JIRA: VSPERF-175
Signed-off-by: Dino Simeon Madarang <dino.simeonx.madarang@intel.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>
Reviewed-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Brian Castelli <brian.castelli@spirent.com>
(cherry picked from commit 76aba6f4fcb5e2a030893c01a3103bf8e94aa288)