ggsn: update gpt-kernel logging to libosmocore

Signed-off-by: Andreas Schultz <aschultz@tpip.net>
diff --git a/ggsn/ggsn.c b/ggsn/ggsn.c
index 821c942..9e8e213 100644
--- a/ggsn/ggsn.c
+++ b/ggsn/ggsn.c
@@ -176,7 +176,7 @@
 	member->peer = pdp;
 
 	if (gtp_kernel_tunnel_add(pdp) < 0) {
-		sys_err(LOG_ERR, __FILE__, __LINE__, 0,
+		SYS_ERR(DGGSN, LOGL_ERROR, 0,
 			"Cannot add tunnel to kernel: %s\n", strerror(errno));
 	}