net: consolidate DHCP onto eth0 only

- rename DfW main interface eth0
- remove eth1 DHCP config
- create tap device in init script not interfaces file

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>

alpine/Dockerfile

@@ -20,6 +20,7 @@ RUN \
   rc-update add vsudd boot && \
   rc-update add sysklogd boot && \
   rc-update add hwclock boot && \
+  rc-update add tap-vsockd boot && \
   rc-update add networking boot && \
   rc-update add acpid default && \
   rc-update add chronyd default && \