Add archfile var and use proper getty for ppc64le
Created by: mtarsel
On ppc64le when net botting Alpine, we will not get a login prompt from Petitboot. This patch will set TTY as /dev/console and the TERMTYPE as vt100 while using a safer BAUD value in order work on varying ppc64le hardware. Additionally I create a archfile variable which is also used to silently fix the apk arch in case the apkovl does not match.
This is in response to https://github.com/alpinelinux/aports/pull/4626