[AETHER-1077] Missing entries in default P4RT mirror store.

Default and Table mirrors were using the same name for their internal EC map.
This was leading to empty EC maps in the standby nodes.

Change-Id: I575dfbf5ba5339f8c94c4e5ed218887a11f14d36
diff --git a/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/mirror/DistributedP4RuntimeMeterMirror.java b/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/mirror/DistributedP4RuntimeMeterMirror.java
index 581c83a..48546fc 100644
--- a/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/mirror/DistributedP4RuntimeMeterMirror.java
+++ b/drivers/p4runtime/src/main/java/org/onosproject/drivers/p4runtime/mirror/DistributedP4RuntimeMeterMirror.java
@@ -33,4 +33,9 @@
     public DistributedP4RuntimeMeterMirror() {
         super(PiEntityType.METER_CELL_CONFIG);
     }
+
+    @Override
+    protected String mapSimpleName() {
+        return PiEntityType.METER_CELL_CONFIG.name().toLowerCase();
+    }
 }