Update PI constant

Using PI constant from Arduino.h instead.

Author: CK-Explorer

src/MadgwickAHRS.cpp

@@ -509,10 +509,10 @@ float Madgwick::getYawRadians() {
 
 /*Convert degree to radian*/
 inline float Madgwick::deg2rad(float value) {
-    return value * M_PI / 180.0f;
+    return value * PI / 180.0f;
 }
 
 /*Convert radian to degree*/
 inline float Madgwick::rad2deg(float value) {
-    return value * 180.0f / M_PI;
+    return value * 180.0f / PI;
 }

src/MadgwickAHRS.h

@@ -17,9 +17,7 @@
 #ifndef MadgwickAHRS_h
 #define MadgwickAHRS_h
 
-#ifndef _USE_MATH_DEFINES
-#define _USE_MATH_DEFINES
-#endif
+#include <Arduino.h>
 #include <math.h>
 
 //-------------------------------------------------------------------------------------------