sgsn: Refactor sgsn_auth to separate request and authorization

Currently the authorization is done in sgsn_auth_request for ACL
based authorization. This doesn't match the way remote authorization
would work, so that there is a second call to sgsn_auth_state already
present in sgsn_auth_update.

This patch removes the autorization check completely from
sgsn_auth_request which in turn calls sgsn_auth_update directly now.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c
index afd3bbb..48fb29d 100644
--- a/openbsc/src/gprs/gprs_gmm.c
+++ b/openbsc/src/gprs/gprs_gmm.c
@@ -644,7 +644,7 @@
 
 	if (ctx->auth_state == SGSN_AUTH_UNKNOWN) {
 		/* Request authorization, this leads to a call to
-		 * sgsn_update_subscriber_data which in turn calls
+		 * sgsn_auth_update which in turn calls
 		 * gsm0408_gprs_access_granted or gsm0408_gprs_access_denied */
 
 		sgsn_auth_request(ctx, &sgsn->cfg);