Update generated dummies for wireguard

[Duss Pirmin]

Hello Genodians

I'm currently adding a RTC-driver (see earlier question by Stefan Thöni 
https://lists.genode.org/pipermail/users/2023-May/008704.html).

To achieve this I need some additional source files from the Kernel 
tree. This leads to some more unresolved symbols that can probably be 
covered by tool/dde_linux/create_dummies. To do this, I need a kernel 
successfully built kernel.

My question is now, how can I get the kernel configuration that was used 
to build the wireguard port? I will have to tweak this to also build the 
RTC stub for Genode.

Regards,
Pirmin