tests: Make go_neg_with_bss_connected 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
the devices.

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

tests/hwsim/test_p2p_channel.py

@@ -207,6 +207,10 @@ def test_autogo_following_bss(dev, apdev):
 def test_go_neg_with_bss_connected(dev, apdev):
     """P2P channel selection: GO negotiation when station interface is connected"""
 
+    dev[0].request("BSS_FLUSH 0")
+    dev[0].request("SCAN freq=2412 only_new=1")
+    dev[1].request("BSS_FLUSH 0")
+    dev[1].request("SCAN freq=2412 only_new=1")
     dev[0].request("SET p2p_no_group_iface 0")
 
     hapd = hostapd.add_ap(apdev[0]['ifname'],