fix: apply rename of osmo_sua_link_get_user_priv()

In the course of a rebase in libosmo-sccp, osmo_sua_link_get_user_priv() was
renamed to osmo_sccp_link_get_user_priv(). Apply this rename here to fix the
build.

Change-Id: I09603f5eb983f17c1e4a1232967fc43c7ceea12a
diff --git a/src/hnbgw_cn.c b/src/hnbgw_cn.c
index e41788d..f97f627 100644
--- a/src/hnbgw_cn.c
+++ b/src/hnbgw_cn.c
@@ -330,7 +330,7 @@
 static int sccp_sap_up(struct osmo_prim_hdr *oph, void *ctx)
 {
 	struct osmo_sccp_link *slink = ctx;
-	struct hnbgw_cnlink *cnlink = osmo_sua_link_get_user_priv(slink);
+	struct hnbgw_cnlink *cnlink = osmo_sccp_link_get_user_priv(slink);
 	struct osmo_scu_prim *prim = (struct osmo_scu_prim *) oph;
 	int rc;