Use explicit parameter for sgsn_auth_init()

This is necessary to properly test ACLs in follow-up patches.

Change-Id: Ibeba371234680f33ad35afbfffce9dca185228c1
diff --git a/src/gprs/sgsn_auth.c b/src/gprs/sgsn_auth.c
index 50f2126..b8d8035 100644
--- a/src/gprs/sgsn_auth.c
+++ b/src/gprs/sgsn_auth.c
@@ -38,7 +38,7 @@
 
 const struct value_string *sgsn_auth_state_names = auth_state_names;
 
-void sgsn_auth_init(void)
+void sgsn_auth_init(struct sgsn_instance *sgsn)
 {
 	INIT_LLIST_HEAD(&sgsn->cfg.imsi_acl);
 }