CS-14421: Fix default interfaces file

I can't see why we set eth0 to dhcp by default. It would result in eth0 want to
get a DHCP address from outside. We should always assign ip through
cloud-early-config for it.

But one point is, the priority of cloud-early-config and networking script is
the same.  So even networking got some ip from outside, cloud-early-config
should able to override it(if cloud-early-config runs after networking) or
networking script won't get dhcp (if cloud-early-config runs before networking),
so I am not quite understand why router would get DHCP address in fact. Maybe
there are other issues.

patches/systemvm/debian/config/etc/init.d/cloud-early-config

@@ -700,7 +700,7 @@ setup_default() {
 auto lo eth0
 iface lo inet loopback
 
-iface eth0 inet dhcp
+iface eth0 inet static
 
 EOF
 }