Move dl_tbf_preemptive_retransmission field from BTS to PCU

Change-Id: I3ab32fcafe83f3ecb116a5b8a05f58f3fddc5451
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index 280e057..6f57e7d 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -545,7 +545,7 @@
 			  force_cs ? " (forced)" : "");
 
 		bsn = create_new_bsn(fn, new_cs);
-	} else if (bts->bts_data()->dl_tbf_preemptive_retransmission && !m_window.window_empty()) {
+	} else if (bts->pcu->vty.dl_tbf_preemptive_retransmission && !m_window.window_empty()) {
 		/* The window contains unacked packages, but not acked.
 		 * Mark unacked bsns as RESEND */
 		LOGPTBFDL(this, LOGL_DEBUG,