Add define for dummy burst string

Change-Id: I464920b3d6d47bb1c797a4ce06230f005a2e06a0
diff --git a/src/gprs_rlcmac.cpp b/src/gprs_rlcmac.cpp
index da5c541..5a223c1 100644
--- a/src/gprs_rlcmac.cpp
+++ b/src/gprs_rlcmac.cpp
@@ -33,7 +33,7 @@
 {
 	LOGP(DRLCMAC, LOGL_NOTICE, "TX: [PCU -> BTS] Paging Request (CCCH)\n");
 	bitvec *paging_request = bitvec_alloc(23, tall_pcu_ctx);
-	bitvec_unhex(paging_request, "2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
+	bitvec_unhex(paging_request, DUMMY_VEC);
 	int plen = Encoding::write_paging_request(paging_request, ptmsi, ptmsi_len);
 	pcu_l1if_tx_pch(paging_request, plen, (char *)imsi);
 	bitvec_free(paging_request);