Fix signal quality return value when it failed to detect

Change-Id: Iae7c57b18e43621be6af076497bdb8480a166d06
diff --git a/edge-monitoring/agent_modem/edge_monitoring_agent_modem.py b/edge-monitoring/agent_modem/edge_monitoring_agent_modem.py
index 6cb581d..f669471 100755
--- a/edge-monitoring/agent_modem/edge_monitoring_agent_modem.py
+++ b/edge-monitoring/agent_modem/edge_monitoring_agent_modem.py
@@ -234,7 +234,7 @@
     success, result = modem.write('AT+CESQ')
     if not success or 'CESQ: ' not in result:
         logging.error("Failed to get signal quality")
-        return 0, 0
+        return { 'rsrq': 0, 'rsrp': 0 }
 
     logging.debug("%s", result)
     tmp_rsrq = result.split('CESQ:')[1].split(',')[4]