Remove an extra param. (#604)

diff --git a/mobly/controllers/sniffer_lib/local/local_base.py b/mobly/controllers/sniffer_lib/local/local_base.py
index 3c1d108..441d60b 100644
--- a/mobly/controllers/sniffer_lib/local/local_base.py
+++ b/mobly/controllers/sniffer_lib/local/local_base.py
@@ -144,8 +144,7 @@
         if self._process is None:
             raise sniffer.InvalidOperationError(
                 "Trying to stop a non-started process")
-        utils.stop_standing_subprocess(self._process,
-                                       kill_signal=signal.SIGINT)
+        utils.stop_standing_subprocess(self._process)
         self._post_process()
 
     def wait_for_capture(self, timeout=None):