[kvm] Re-enable test_po_update for KVM test (#2408)

Signed-off-by: Danny Allen <daall@microsoft.com>

tests/kvmtest.sh

@@ -57,6 +57,7 @@ cacl/test_cacl_function.py \
 dhcp_relay/test_dhcp_relay.py \
 ntp/test_ntp.py \
 pc/test_po_cleanup.py \
+pc/test_po_update.py \
 route/test_default_route.py \
 snmp/test_snmp_cpu.py \
 snmp/test_snmp_interfaces.py \
@@ -82,9 +83,6 @@ platform_tests/test_cpu_memory_usage.py"
 # enable LLDP testing again.
 # lldp/test_lldp.py
 
-# FIXME: This test has been disabled and needs to be fixed and put back in:
-# pc/test_po_update.py
-
 pushd $SONIC_MGMT_DIR/tests
 ./run_tests.sh $PYTEST_CLI_COMMON_OPTS -c "$tests" -p logs/$tgname
 popd