tests: Make concurrent_grpform_while_connecting2 more robust

It was possible for this test case to fail due to PBC overlap that was
detected based on previous test case having used PBC. Make that false
positive less likely to happen by explicitly clearing the scan cache on
dev[1].

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

tests/hwsim/test_p2p_concurrency.py

@@ -119,6 +119,8 @@ def test_concurrent_grpform_while_connecting2(dev, apdev):
     logger.info("Start connection to an infrastructure AP")
     hostapd.add_ap(apdev[0]['ifname'], { "ssid": "test-open" })
     dev[0].connect("test-open", key_mgmt="NONE", wait_connect=False)
+    dev[1].request("BSS_FLUSH 0")
+    dev[1].scan(freq="2412", only_new=True)
 
     logger.info("Form a P2P group while connecting to an AP")
     dev[0].request("SET p2p_no_group_iface 0")