Don't double-free characteristics

Author: facchinm

src/utility/GATT.cpp

@@ -70,19 +70,19 @@ void GATTClass::begin()
 
 void GATTClass::end()
 {
-  if (_genericAccessService->release() <= 0)
+  if (_genericAccessService->release() == 0)
     delete(_genericAccessService);
 
-  if (_deviceNameCharacteristic->release() <= 0)
+  if (_deviceNameCharacteristic->release() == 0)
     delete(_deviceNameCharacteristic);
 
-  if (_appearanceCharacteristic->release() <= 0)
+  if (_appearanceCharacteristic->release() == 0)
     delete(_appearanceCharacteristic);
 
-  if (_genericAttributeService->release() <= 0)
+  if (_genericAttributeService->release() == 0)
     delete(_genericAttributeService);
 
-  if (_servicesChangedCharacteristic->release() <= 0)
+  if (_servicesChangedCharacteristic->release() == 0)
     delete(_servicesChangedCharacteristic);
 
   clearAttributes();