Configure Alpine networking via ip kernel command line

[mmlb]

Expected Behaviour

Remove need for configuring Alpine networking via dhcp.

Current Behaviour

A simple bounded retry loop with hard coded sleep times before, during and after calling udhcpc.

Possible Solution

Alpine's init supports ip configuration via the ip kernel command line.
We have not been using it because it bypassed the nic detection logic (which we probably should have just changed anyway..) and did not support dns configuration.
But now that all changes with tinkerbell/osie#72 so we should just make use of ip at some point.

[tstromberg]

@mmlb - is this still a valid issue?

[mmlb]

Nope lets kill this as its not likely to be useful to non-alpine OSes.