Move anti-windup iterm reset from rx loop to pid loop

Having the iterm resetting happening in the rx loop causes a sawtooth PID/motor effect while idling since the PID loop is running at a much higher rate and iterm is allowed to grow during this, and then only reset at a much lower rate in the rx loop. This can potentially lead to some oscillation and/or resonance while idling before takeoff as the sawtooth signal can make it through to the motor outputs.

src/main/flight/pid.c

@@ -80,6 +80,7 @@ static FAST_RAM_ZERO_INIT float antiGravityThrottleHpf;
 static FAST_RAM_ZERO_INIT uint16_t itermAcceleratorGain;
 static FAST_RAM float antiGravityOsdCutoff = 1.0f;
 static FAST_RAM_ZERO_INIT bool antiGravityEnabled;
+static FAST_RAM_ZERO_INIT bool zeroThrottleItermReset;
 
 PG_REGISTER_WITH_RESET_TEMPLATE(pidConfig_t, pidConfig, PG_PID_CONFIG, 2);
 
@@ -1392,6 +1393,8 @@ void FAST_CODE pidController(const pidProfile_t *pidProfile, const rollAndPitchT
 
             pidData[axis].Sum = 0;
         }
+    } else if (zeroThrottleItermReset) {
+        pidResetIterm();
     }
 }
 
@@ -1444,3 +1447,8 @@ void dynLpfDTermUpdate(float throttle)
     }
 }
 #endif
+
+void pidSetItermReset(bool enabled)
+{
+    zeroThrottleItermReset = enabled;
+}