Add packet_capture judgment check on teardown_test

Bug:322894822
Change-Id: I33a707b45c3b475b3e088dce85ba0a3586d4b4d8
diff --git a/acts_tests/tests/google/wifi/WifiIOTConnectionTest.py b/acts_tests/tests/google/wifi/WifiIOTConnectionTest.py
index 382c4de..1a3f194 100644
--- a/acts_tests/tests/google/wifi/WifiIOTConnectionTest.py
+++ b/acts_tests/tests/google/wifi/WifiIOTConnectionTest.py
@@ -65,7 +65,8 @@
     def teardown_test(self):
         self.dut.droid.wakeLockRelease()
         self.dut.droid.goToSleepNow()
-        wutils.stop_pcap(self.packet_capture, self.pcap_procs, False)
+        if hasattr(self, 'packet_capture'):
+            wutils.stop_pcap(self.packet_capture, self.pcap_procs, False)
 
     def on_fail(self, test_name, begin_time):
         self.dut.take_bug_report(test_name, begin_time)