Allow multiple bts objects in PCU

This patch doesn't really tests whether osmo-pcu can work on a multi-bts
environment, but it prepares the data structures to be able to do so at
any later point in time.

Change-Id: I6b10913f46c19d438c4e250a436a7446694b725a
diff --git a/tests/fn/FnTest.cpp b/tests/fn/FnTest.cpp
index dd30b34..4281fc3 100644
--- a/tests/fn/FnTest.cpp
+++ b/tests/fn/FnTest.cpp
@@ -53,7 +53,7 @@
 
 static void run_test()
 {
-	struct gprs_rlcmac_bts *bts = bts_alloc(the_pcu);
+	struct gprs_rlcmac_bts *bts = bts_alloc(the_pcu, 0);
 	uint32_t fn;
 
 	printf("RFN_MODULUS=%i\n",RFN_MODULUS);