Return meaningful BCM Error String instead of cryptic error
code numbers to caller in case BAL-API/Internal failures.

Change-Id: Iab306f4ec44d7e74f9434ff70c199fdaafb1e76c
diff --git a/agent/src/error_format.cc b/agent/src/error_format.cc
index f8de289..8460527 100644
--- a/agent/src/error_format.cc
+++ b/agent/src/error_format.cc
@@ -50,8 +50,8 @@
             break;
     }
 
-    message.append(" BCM Error ");
-    message.append(std::to_string(bcm_err));
+    message.append(" BCM Error: ");
+    message.append(bcmos_strerror(bcm_err));
 
     return Status(grpc_err, message);
 }