Increase NAV_LOITER_RAD and RTL_LOITER_RAD to 80m each

For many VTOLs/fixed-wing drones a 50m loiter radius is too tight, and
going to 80m is a better and safer default.

Signed-off-by: Silvan Fuhrer <silvan@auterion.com>

src/modules/navigator/navigator_params.c

@@ -52,7 +52,7 @@
  * @increment 0.5
  * @group Mission
  */
-PARAM_DEFINE_FLOAT(NAV_LOITER_RAD, 50.0f);
+PARAM_DEFINE_FLOAT(NAV_LOITER_RAD, 80.0f);
 
 /**
  * Acceptance Radius

src/modules/navigator/rtl_params.c

@@ -161,7 +161,7 @@ PARAM_DEFINE_INT32(RTL_PLD_MD, 0);
  * @increment 0.5
  * @group Return Mode
  */
-PARAM_DEFINE_FLOAT(RTL_LOITER_RAD, 50.0f);
+PARAM_DEFINE_FLOAT(RTL_LOITER_RAD, 80.0f);
 
 /**
  * RTL heading mode