When re-downloaded the whole kernel again and applied all the recommended patches (from your earlier post) with the 'git apply', I didn't get the compilation error. I just checked and this code, you mentioned in this post, is still in the source.
Do I need to keep it or remove it?

On the other hand I flashed this kernel on the wip0.15 and deleted the 'lib/systemd/system/droid-hcismd-up.service' and the 'bluetooth.service.wants' folder because they were related to the hadk's bluetooth solution, but the bluetooth still not work.

Maybe there is something else in the kernel config to switch on or off? And/or another patch to apply?
Thank you.