Revert "Plane: allow quadplanes to scale ESC CAN like normal"

this change can cause a flyaway if you have low SERVO3_MAX for
k_throttle. This can be reproduced with -f quadplane-can

ArduPlane/radio.cpp

@@ -49,9 +49,16 @@ void Plane::set_control_channels(void)
     quadplane.rc_fwd_thr_ch = rc().find_channel_for_option(RC_Channel::AUX_FUNC::FWD_THR);
 #endif
 
-    // setup correct scaling for ESCs like the UAVCAN ESCs which
-    // take a proportion of speed.
-    g2.servo_channels.set_esc_scaling_for(SRV_Channel::k_throttle);
+    bool set_throttle_esc_scaling = true;
+#if HAL_QUADPLANE_ENABLED
+    set_throttle_esc_scaling = !quadplane.enable;
+#endif
+    if (set_throttle_esc_scaling) {
+        // setup correct scaling for ESCs like the UAVCAN ESCs which
+        // take a proportion of speed. For quadplanes we use AP_Motors
+        // scaling
+        g2.servo_channels.set_esc_scaling_for(SRV_Channel::k_throttle);
+    }
 }
 
 /*