mixer: minor refactoring to reduce header include dependencies

- avoid including <px4_defines.h> from the math headers
- avoid driver include <drivers/drv_mixer.h> from the mixer

src/lib/FlightTasks/tasks/Utility/ManualSmoothingXY.cpp

@@ -38,6 +38,7 @@
 #include "ManualSmoothingXY.hpp"
 #include <mathlib/mathlib.h>
 #include <float.h>
+#include <px4_defines.h>
 
 using namespace matrix;
 

src/lib/FlightTasks/tasks/Utility/StraightLine.cpp

@@ -38,6 +38,7 @@
 #include "StraightLine.hpp"
 #include <mathlib/mathlib.h>
 #include <float.h>
+#include <px4_defines.h>
 
 #define VEL_ZERO_THRESHOLD 0.001f // Threshold to compare if the target velocity is zero
 #define DECELERATION_MAX 8.0f     // The vehicles maximum deceleration TODO check to create param

src/lib/FlightTasks/tasks/Utility/VelocitySmoothing.cpp

@@ -36,6 +36,7 @@
 #include <cstdio>
 #include <float.h>
 #include <math.h>
+#include <px4_defines.h>
 
 #include <mathlib/mathlib.h>