AP_Tuning: FIX no double math

Author: Yury-MonZon

libraries/AP_Tuning/AP_Tuning.cpp

@@ -228,7 +228,7 @@ void AP_Tuning::check_input(uint8_t flightmode)
     need_revert |= (1U << current_parm_index);
     set_value(current_parm, new_value);
 
-    if ( fabs(new_value-old_value) > (0.05 * old_value) ) {
+    if ( fabsf(new_value-old_value) > (0.05 * old_value) ) {
         old_value = new_value;
         GCS_SEND_TEXT(MAV_SEVERITY_INFO, 
             "Tuning %s%s%0.4f",