don't re-implement osmo_talloc_replace_string()

osmo_talloc_replace_string() was introducd into libosmocore in 2014, see
commit f3c7e85d05f7b2b7bf093162b776f71b2bc6420d

There's no reason for us to re-implement this as bsc_replace_string
here.

Change-Id: I6d2fcaabbc74730f6f491a2b2d5c784ccafc6602
diff --git a/openbsc/src/libbsc/bsc_vty.c b/openbsc/src/libbsc/bsc_vty.c
index 0ee2390..b05d3d9 100644
--- a/openbsc/src/libbsc/bsc_vty.c
+++ b/openbsc/src/libbsc/bsc_vty.c
@@ -2946,7 +2946,7 @@
 	struct gsm_bts *bts = vty->index;
 	int rc;
 
-	bsc_replace_string(bts, &bts->pcu_sock_path, argv[0]);
+	osmo_talloc_replace_string(bts, &bts->pcu_sock_path, argv[0]);
 	pcu_sock_exit(bts);
 	rc = pcu_sock_init(bts->pcu_sock_path, bts);
 	if (rc < 0) {