remove pcu own bitvector implementation

The osmocore bitvec is exact the same, but use a pointer instead of
a reference.

Change-Id: Id8f797631d89aa12b6e48efb2dc153a3e2f059f7
diff --git a/src/tbf_ul.cpp b/src/tbf_ul.cpp
index 2598174..1eee41a 100644
--- a/src/tbf_ul.cpp
+++ b/src/tbf_ul.cpp
@@ -121,7 +121,7 @@
 	msg = msgb_alloc(23, "rlcmac_ul_ack");
 	if (!msg)
 		return NULL;
-	bitvec *ack_vec = bitvec_alloc(23);
+	bitvec *ack_vec = bitvec_alloc(23, tall_pcu_ctx);
 	if (!ack_vec) {
 		msgb_free(msg);
 		return NULL;