{enb,epc,ms}_srs: refactor start/stop and KPI helpers

refactor some of the functionality to srslte_common

Change-Id: I2ff36df6f1a07ed8ddac39d296d62fe44a215283
diff --git a/src/osmo_gsm_tester/obj/enb_srs.py b/src/osmo_gsm_tester/obj/enb_srs.py
index 13d18f3..ec2d1fc 100644
--- a/src/osmo_gsm_tester/obj/enb_srs.py
+++ b/src/osmo_gsm_tester/obj/enb_srs.py
@@ -51,6 +51,7 @@
 
     def __init__(self, testenv, conf):
         super().__init__(testenv, conf, srsENB.BINFILE)
+        srslte_common.__init__(self)
         self.ue = None
         self.run_dir = None
         self.gen_conf = None
@@ -73,6 +74,7 @@
         self.metrics_file = None
         self.stop_sleep_time = 6 # We require at most 5s to stop
         self.testenv = testenv
+        self.kpis = None
         self._additional_args = []
         if not rf_type_valid(conf.get('rf_dev_type', None)):
             raise log.Error('Invalid rf_dev_type=%s' % conf.get('rf_dev_type', None))
@@ -100,12 +102,6 @@
         # Collect KPIs for each TC
         self.testenv.test().set_kpis(self.get_kpis())
 
-    def sleep_after_stop(self):
-        # Only sleep once
-        if self.stop_sleep_time > 0:
-            MainLoop.sleep(self.stop_sleep_time)
-            self.stop_sleep_time = 0
-
     def start(self, epc):
         self.log('Starting srsENB')
         self._epc = epc