tests: Try to keep GAS frames within gas_concurrent_scan capture

With UML time-travel, it was possible for a GAS frame to end up in the
capture file for the next test case and if that next case used tshark to
count the number of frames (which is done, e.g., in
gas_anqp_address3_assoc), the following test case could have indicated
failure even when everything worked correctly.

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

tests/hwsim/test_gas.py

@@ -191,7 +191,7 @@ def test_gas_concurrent_scan(dev, apdev):
     bssid = apdev[0]['bssid']
     params = hs20_ap_params()
     params['hessid'] = bssid
-    hostapd.add_ap(apdev[0], params)
+    hapd = hostapd.add_ap(apdev[0], params)
 
     # get BSS entry available to allow GAS query
     dev[0].scan_for_bss(bssid, freq="2412", force_scan=True)
@@ -224,6 +224,10 @@ def test_gas_concurrent_scan(dev, apdev):
     if responses != 4:
         raise Exception("Unexpected number of GAS responses")
 
+    # Try to get all GAS frames into the sniffer capture of this test case.
+    hapd.disable()
+    time.sleep(0.1)
+
 def test_gas_concurrent_connect(dev, apdev):
     """Generic GAS queries with concurrent connection operation"""
     skip_with_fips(dev[0])