ggsn: update gpt-kernel logging to libosmocore

Signed-off-by: Andreas Schultz <aschultz@tpip.net>
diff --git a/ggsn/gtp-kernel.h b/ggsn/gtp-kernel.h
index 7bf533d..628002f 100644
--- a/ggsn/gtp-kernel.h
+++ b/ggsn/gtp-kernel.h
@@ -23,7 +23,7 @@
 				  struct gengetopt_args_info *args_info)
 {
 	if (args_info->gtpnl_given) {
-		sys_err(LOG_ERR, __FILE__, __LINE__, 0,
+		SYS_ERR(DGGSN, LOGL_ERROR, 0,
 			"ggsn compiled without GTP kernel support!\n");
 		return -1;
 	}