pcu_l1_if.cpp: handle TLLI based IMMEDIATE ASSIGNMENT confirmation

The IMMEDIATE ASSIGNMENT for downlink TBFs must be confirmed by the
receiving end (BSC/BTS) in order to set the timers in the PCU correctly.

When the PCU is used in a BSC co-located scheme (Ericsson RBS). The TLLI
is used as an identifier to confirm a specific IMMEDIATE ASSIGNMENT.

Change-Id: Icf7ca34500984239ee877ee71fd9c126b5eb3480
Related: OS#5198
diff --git a/src/bts.h b/src/bts.h
index 61c5e43..5efbdad 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -315,7 +315,7 @@
 
 int bts_rcv_rach(struct gprs_rlcmac_bts *bts, const struct rach_ind_params *rip);
 int bts_rcv_ptcch_rach(struct gprs_rlcmac_bts *bts, const struct rach_ind_params *rip);
-int bts_rcv_imm_ass_cnf(struct gprs_rlcmac_bts *bts, const uint8_t *data, uint32_t fn);
+int bts_rcv_imm_ass_cnf(struct gprs_rlcmac_bts *bts, const uint8_t *data, uint32_t tlli, uint32_t fn);
 
 void bts_send_gsmtap(struct gprs_rlcmac_bts *bts,
 		     enum pcu_gsmtap_category categ, bool uplink, uint8_t trx_no,