tbf_ul_ack_fsm: Pass ul_tbf instead of generic tbf

The UL_ACK_NACK FSM is only used in Uplink TBFs.

Change-Id: Ic9893d274f4b6fafc75a615f7d6dcb9433b94ace
diff --git a/src/tbf_ul_ack_fsm.h b/src/tbf_ul_ack_fsm.h
index d2e9332..f25972e 100644
--- a/src/tbf_ul_ack_fsm.h
+++ b/src/tbf_ul_ack_fsm.h
@@ -62,7 +62,7 @@
 };
 
 
-struct msgb *tbf_ul_ack_create_rlcmac_msg(const struct gprs_rlcmac_tbf *tbf, uint32_t fn, uint8_t ts);
-bool tbf_ul_ack_rts(const struct gprs_rlcmac_tbf *tbf);
-bool tbf_ul_ack_waiting_cnf_final_ack(const struct gprs_rlcmac_tbf *tbf);
-bool tbf_ul_ack_exp_ctrl_ack(const struct gprs_rlcmac_tbf *tbf, uint32_t fn, uint8_t ts);
+struct msgb *tbf_ul_ack_create_rlcmac_msg(const struct gprs_rlcmac_ul_tbf *ul_tbf, uint32_t fn, uint8_t ts);
+bool tbf_ul_ack_rts(const struct gprs_rlcmac_ul_tbf *ul_tbf);
+bool tbf_ul_ack_waiting_cnf_final_ack(const struct gprs_rlcmac_ul_tbf *ul_tbf);
+bool tbf_ul_ack_exp_ctrl_ack(const struct gprs_rlcmac_ul_tbf *ul_tbf, uint32_t fn, uint8_t ts);