Apply TERN to compact code (#17619)

Marlin/src/HAL/STM32F1/Servo.cpp

@@ -138,9 +138,7 @@ void libServo::move(const int32_t value) {
     angle = constrain(value, minAngle, maxAngle);
     servoWrite(pin, US_TO_COMPARE(ANGLE_TO_US(angle)));
     safe_delay(servo_delay[servoIndex]);
-    #if ENABLED(DEACTIVATE_SERVOS_AFTER_MOVE)
-      detach();
-    #endif
+    TERN_(DEACTIVATE_SERVOS_AFTER_MOVE, detach());
   }
 }