Disable dhcpcd in test_port_security_macspoofing_port

Cirros 0.6.0+ switched to dhcpcd and dhcpcd by default it
configures all the interfaces. In port_security_macspoofing_port
test we spoof mac address and re assign ip address, but dhcpcd
interfares with it and causes issues. Let's disable dhcpcd
before reconfiguring the interface.

Closes-Bug: #2008062
Change-Id: I75cf0477ae4195121c87bde6d276fa51c3d094aa
diff --git a/tempest/scenario/test_network_basic_ops.py b/tempest/scenario/test_network_basic_ops.py
index cbe4122..7b819e0 100644
--- a/tempest/scenario/test_network_basic_ops.py
+++ b/tempest/scenario/test_network_basic_ops.py
@@ -898,10 +898,13 @@
                                        nic=spoof_nic, should_succeed=True)
         # Set a mac address by making nic down temporary
         spoof_ip_addresses = ssh_client.get_nic_ip_addresses(spoof_nic)
-        cmd = ("sudo ip link set {nic} down;"
+        dhcp_cmd = ("sudo start-stop-daemon -K -x /sbin/dhcpcd -p "
+                    "/var/run/dhcpcd/pid -o || true")
+        cmd = ("{dhcp_cmd}; sudo ip link set {nic} down;"
                "sudo ip link set dev {nic} address {mac};"
                "sudo ip link set {nic} up;"
                "sudo ip address flush dev {nic};").format(nic=spoof_nic,
+                                                          dhcp_cmd=dhcp_cmd,
                                                           mac=spoof_mac)
         for ip_address in spoof_ip_addresses:
             cmd += (