device-purism-librem5: enable ship mode for usb charge controller

Ship mode via the mechanism used by purism doesn't work; it's either not possible or outside my understanding to run an openrc runscript with a busybox init on poweroff and not reboot, which is what is required for this to work properly..

This module param requires a corresponding kernel patch to enable ship mode support in the bq25890-charger module

Ship mode is a power state for the charge controller that causes the controller to remove all power from the rest of the system. Without ship mode, the L5 will continue to slowly drain the battery even when it is "off", resulting in the battery being completely drained after a couple of days or so. With ship mode, there was maybe a 1% drain over a 4 day period when I had the phone powered off (and that 1% may have just been power used from booting it back up to measure battery capacity...)