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/src/gprs_pcu.h b/src/gprs_pcu.h
index 37f6e07..058d102 100644
--- a/src/gprs_pcu.h
+++ b/src/gprs_pcu.h
@@ -107,7 +107,7 @@
 	struct gsmtap_inst *gsmtap;
 	uint32_t gsmtap_categ_mask;
 
-	struct gprs_rlcmac_bts *bts;
+	struct llist_head bts_list; /* list of gprs_rlcmac_tbf */
 
 	struct gprs_ns2_inst *nsi;
 
@@ -123,6 +123,8 @@
 
 struct gprs_pcu *gprs_pcu_alloc(void *ctx);
 
+struct gprs_rlcmac_bts *gprs_pcu_get_bts_by_nr(struct gprs_pcu *pcu, uint8_t bts_nr);
+
 void gprs_pcu_set_initial_cs(struct gprs_pcu *pcu, uint8_t cs_dl, uint8_t cs_ul);
 void gprs_pcu_set_initial_mcs(struct gprs_pcu *pcu, uint8_t mcs_dl, uint8_t mcs_ul);
 void gprs_pcu_set_max_cs(struct gprs_pcu *pcu, uint8_t cs_dl, uint8_t cs_ul);