Get rid of singleton gprs_bssgp_pcu_current_bctx()

Access it from existing pointers instead.

Change-Id: I77455da5221090ebea142ecd49d5dba0065bfc5c
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index 8ae74d5..d7590e1 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -782,7 +782,7 @@
 
 static int pcu_rx_susp_req(struct gprs_rlcmac_bts *bts, struct gsm_pcu_if_susp_req *susp_req)
 {
-	struct bssgp_bvc_ctx *bctx = gprs_bssgp_pcu_current_bctx();
+	struct bssgp_bvc_ctx *bctx = bts->pcu->bssgp.bctx;
 	GprsMs *ms;
 	struct gprs_rlcmac_dl_tbf *dl_tbf;
 	struct gprs_rlcmac_ul_tbf *ul_tbf;