osmo-trx: Enable multi_arfcn for B200 and only in multiTRX setup

Change-Id: I6a29e1813f0603b00b49b7b7c805be23a72cf0e3
diff --git a/example/resources.conf.prod b/example/resources.conf.prod
index e3c5ad8..88358ac 100644
--- a/example/resources.conf.prod
+++ b/example/resources.conf.prod
@@ -30,6 +30,7 @@
     remote_user: jenkins
     trx_ip: 10.42.42.230
     clock_reference: external
+    multi_arfcn: true
 
 - label: sysmoCell 5000
   type: osmo-bts-trx