skeleton: remove loopback interface configuration from inittab

The lo interface is marked auto in /etc/network/interfaces, so the
configuration of the loopback network interface is part of the
S40network init script. This causes the "RTNETLINK answers: File exists" error
message to appear at startup time.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>