ms: Set default CoDel interval to 4s

The current default interval is 2s which seems to be too short when
the DL TBF has to be established. This may cause freezing or really
slow TCP connections.

This commit increases the default value to 4s. When the
dl-tbf-idle-time is set, DL TBF are established less frequent, so
smaller values (like 2s or below) can be used to improve the average
latency when the load is high.

Sponsored-by: On-Waves ehf

src/gprs_ms.cpp

@@ -33,7 +33,7 @@ extern "C" {
 	#include <osmocom/core/utils.h>
 }
 
-#define GPRS_CODEL_SLOW_INTERVAL_MS 2000
+#define GPRS_CODEL_SLOW_INTERVAL_MS 4000
 
 extern void *tall_pcu_ctx;