SITL: reduce default GPS delay to 0.4

closer to real uBlox delay

libraries/SITL/SITL.cpp

@@ -32,7 +32,7 @@ const AP_Param::GroupInfo SITL::var_info[] PROGMEM = {
     AP_GROUPINFO("GPS_DISABLE",4, SITL,  gps_disable, 0),
     AP_GROUPINFO("DRIFT_SPEED",5, SITL,  drift_speed, 0.2),
     AP_GROUPINFO("DRIFT_TIME", 6, SITL,  drift_time,  5),
-    AP_GROUPINFO("GPS_DELAY",  7, SITL,  gps_delay,   4),
+    AP_GROUPINFO("GPS_DELAY",  7, SITL,  gps_delay,   2),
     AP_GROUPINFO("ENGINE_MUL", 8, SITL,  engine_mul,  1),
     AP_GROUPINFO("WIND_SPD",   9, SITL,  wind_speed,  0),
     AP_GROUPINFO("WIND_DIR",  10, SITL,  wind_direction,  180),