pcu.py: Introduce PcuDummy class

It will be used in later commits by BTS without proper PCU control such
as NanoBts.

Change-Id: I37ba38f7d81134e5f0ca28fa684fdb09c753bb04
diff --git a/src/osmo_gsm_tester/pcu.py b/src/osmo_gsm_tester/pcu.py
index 0eddb06..97d0b92 100644
--- a/src/osmo_gsm_tester/pcu.py
+++ b/src/osmo_gsm_tester/pcu.py
@@ -46,4 +46,15 @@
         """Start the PCU. Must be implemented by subclass."""
         pass
 
+#------------------------------------------------------------------------------
+
+class PcuDummy(Pcu):
+    """PCU for BTS without proper PCU control"""
+
+    def __init__(self, suite_run, bts, conf):
+        super().__init__(suite_run, bts, conf, 'PcuDummy')
+
+    def start(self):
+        pass
+
 # vim: expandtab tabstop=4 shiftwidth=4