buildroot

system: do not handle network settings for custom skeleton

We expect the custom skeleton to be fully filled with the necessary
files, now. There is definitely no reason we should handle network
settings in there. A user using a custom skeleton should be fully
responsible for providing a functional skeleton.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>