tbf_fsm: Introduce new event TBF_EV_FIRST_UL_DATA_RECVD

This allows easier tracking of this event. It will also extended later
on with more logic which is better placed in tbf_fsm.

Change-Id: I5c935914e13db3928c32621ec04eb2760367615d
diff --git a/src/tbf_fsm.h b/src/tbf_fsm.h
index 22266e7..903bcd7 100644
--- a/src/tbf_fsm.h
+++ b/src/tbf_fsm.h
@@ -28,6 +28,7 @@
 	TBF_EV_ASSIGN_ACK_PACCH, /*  We received a CTRL ACK confirming assignment started on PACCH */
 	TBF_EV_ASSIGN_READY_CCCH, /* TBF Start Time timer triggered */
 	TBF_EV_ASSIGN_PCUIF_CNF, /* Transmission of IMM.ASS for DL TBF to the MS confirmed by BTS over PCUIF */
+	TBF_EV_FIRST_UL_DATA_RECVD, /* UL TBF: Received first UL data from MS. Equals to Contention Resolution completed on the network side */
 	TBF_EV_DL_ACKNACK_MISS, /* DL TBF: We polled for DL ACK/NACK but we received none (POLL timeout) */
 	TBF_EV_LAST_DL_DATA_SENT, /* DL TBF sends RLCMAC block containing last DL avilable data buffered */
 	TBF_EV_LAST_UL_DATA_RECVD, /* UL TBF sends RLCMAC block containing last UL data (cv=0) */