Add carrier ID to telecom metrics proto

Add the carrier ID so it can be used in server-side aggregation

Bug: 119153703
Test: unit, manual
Change-Id: I10212411741850169ecb7712f60b2275620b3943
diff --git a/proto/telecom.proto b/proto/telecom.proto
index 2f4fae8..73eba87 100644
--- a/proto/telecom.proto
+++ b/proto/telecom.proto
@@ -16,6 +16,9 @@
 
   // Hardware revision (EVT, DVT, PVT etc.)
   optional string hardware_revision = 3;
+
+  // Carrier ID that the device is associated to
+  optional int32 carrier_id = 4;
 }
 
 message LogSessionTiming {