message: fix volatility of can config
diff: @@ -27,8 +27,6 @@ uint32_t _reboot_cookie __attribute__ ((section (".noinit")));
  extern char _estack; // provided by the linker script
  -ODriveCAN::Config_t can_config;
  -CANSimple *can_simple = nullptr;
  ODrive odrv{};
  @@ -89,7 +87,7 @@ void StatusLedController::update() {
  static bool config_read_all() {
  bool success = board_read_config() &&
  config_manager.read(&odrv.config_) &&
  - config_manager.read(&can_config);
  + config_manager.read(&odrv.can_.config_);
  for (size_t i = 0; (i < AXIS_COUNT) && success; ++i) {
  success = config_manager.read(&encoders[i].config_) &&
  config_manager.read(&axes[i].sensorless_estimator_.config_) &&
  @@ -109,7 +107,7 @@ static bool config_read_all() {
  static bool config_write_all() {
  bool success = board_write_config() &&
  config_manager.write(&odrv.config_) &&
  - config_manager.write(&can_config);
  + config_manager.write(&odrv.can_.config_);
  for (size_t i = 0; (i < AXIS_COUNT) && success; ++i) {
  success = config_manager.write(&encoders[i].config_) &&
  config_manager.write(&axes[i].sensorless_estimator_.config_) &&
  @@ -128,7 +126,7 @@ static bool config_write_all() {
  static void config_clear_all() {
  odrv.config_ = {};
  - can_config = {};
  + odrv.can_.config_ = {};
  for (size_t i = 0; i < AXIS_COUNT; ++i) {
  encoders[i].config_ = {};
  axes[i].sensorless_estimator_.config_ = {};
  