fix(nimble): Fix unused variable warnings

Author: lucasssvaz

libraries/BLE/src/BLEDevice.cpp

@@ -236,7 +236,7 @@ String BLEDevice::getValue(BLEAddress bdAddress, BLEUUID serviceUUID, BLEUUID ch
  */
 void BLEDevice::init(String deviceName) {
   if (!initialized) {
-    esp_err_t errRc = ESP_OK;
+    [[maybe_unused]] esp_err_t errRc = ESP_OK;
 #if defined(ARDUINO_ARCH_ESP32) && !defined(CONFIG_NIMBLE_ENABLED)
     if (!btStart()) {
       errRc = ESP_FAIL;

libraries/BLE/src/BLEServer.cpp

@@ -537,7 +537,7 @@ void BLEServerCallbacks::onDisconnect(BLEServer *pServer, esp_ble_gatts_cb_param
 }  // onDisconnect
 
 void BLEServerCallbacks::onMtuChanged(BLEServer *pServer, esp_ble_gatts_cb_param_t *param) {
-  uint16_t mtu = param->mtu.mtu;
+  [[maybe_unused]] uint16_t mtu = param->mtu.mtu;
   log_d("BLEServerCallbacks", ">> onMtuChanged(): Default");
   log_d("BLEServerCallbacks", "Device: %s MTU: %d", BLEDevice::toString().c_str(), mtu);
   log_d("BLEServerCallbacks", "<< onMtuChanged()");