Add channel_allocator cfg attr to bts resources

Change-Id: I682809d4aeb91a36e3a35fc481e8d40d0b084fa0
diff --git a/src/osmo_gsm_tester/templates/osmo-bsc.cfg.tmpl b/src/osmo_gsm_tester/templates/osmo-bsc.cfg.tmpl
index 18303b6..edcf33f 100644
--- a/src/osmo_gsm_tester/templates/osmo-bsc.cfg.tmpl
+++ b/src/osmo_gsm_tester/templates/osmo-bsc.cfg.tmpl
@@ -49,7 +49,7 @@
   ms max power 33
   cell reselection hysteresis 4
   rxlev access min 0
-  channel allocator ascending
+  channel allocator ${bts.channel_allocator}
   rach tx integer 9
   rach max transmission 7
 % if bsc.net.get('rsl_ip', False):