tests: Make MACsec test cases clear monitor socket more thoroughly

The wpas (dev5) control interface socket did not always get cleared in
the MACsec test cases and this could result in issues with following
test cases if the dev5 message queue hit the maximum limit.

Signed-off-by: Jouni Malinen <j@w1.fi>

tests/hwsim/test_macsec.py

@@ -325,6 +325,7 @@ def cleanup_macsec_br(count):
         wpas.interface_remove("veth%d" % i)
         subprocess.call(["ip", "link", "del", "veth%d" % i],
                         stderr=open('/dev/null', 'w'))
+    del wpas
     subprocess.call(["ip", "link", "set", "brveth", "down"])
     subprocess.call(["brctl", "delbr", "brveth"])
 
@@ -427,6 +428,11 @@ def run_macsec_psk_br(dev, apdev, count, mka_priority):
         else:
             logger.info("Data traffic test failed - ignore for now for >= 3 device cases")
 
+    for i in range(count):
+        wpa[i].dump_monitor()
+    for i in range(count):
+        del wpa[0]
+
 def test_macsec_psk_ns(dev, apdev, params):
     """MACsec PSK (netns)"""
     try: