Copter: fix spelling in drift mode variable name

non-functional change

ArduCopter/mode_drift.cpp

@@ -40,7 +40,7 @@ bool Copter::ModeDrift::init(bool ignore_checks)
 // should be called at 100hz or more
 void Copter::ModeDrift::run()
 {
-    static float breaker = 0.0f;
+    static float braker = 0.0f;
     static float roll_input = 0.0f;
     float target_roll, target_pitch;
     float target_yaw_rate;
@@ -90,11 +90,11 @@ void Copter::ModeDrift::run()
     // If we let go of sticks, bring us to a stop
     if(is_zero(target_pitch)){
         // .14/ (.03 * 100) = 4.6 seconds till full braking
-        breaker += .03f;
-        breaker = MIN(breaker, DRIFT_SPEEDGAIN);
-        target_pitch = pitch_vel * breaker;
+        braker += .03f;
+        braker = MIN(braker, DRIFT_SPEEDGAIN);
+        target_pitch = pitch_vel * braker;
     }else{
-        breaker = 0.0f;
+        braker = 0.0f;
     }
 
     // set motors to full range