ports: Change ports settings file to /etc/network/${port}/settings

ports: Change ports settings file to /etc/network/${port}/settings

The configuration of a port was stored in a file called:
/etc/network/${port}
This is bad because it is very hard to add further information
which belong primary not to the configuration to this file.

So we change the settings file to /etc/network/${port}/settings like for the zones.

This make it possible to store other configurations like the color in other files in the directory
/etc/network/${port}.

A workaround to move the config file into the new directory scheme is:
port=p1 && mv /etc/network/ports/${port} /etc/network/ports/${port}-save \
&& mkdir -p /etc/network/ports/${port} \
&& mv /etc/network/ports/${port}-save /etc/network/ports/${port}/settings

where port is the name of the port like p1 or p0.

Signed-off-by: Jonatan Schlag <jonatan.schlag@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>