Direct wire KSCAN driver needs to be migrated to PORT events

[petejohanson]

As part of the deep sleep work in #211, we moved the matrix KSCAN driver to using the nrf "PORT" events, which enables key presses to wake from sleep, and reduces power usage, and allows for more "input pins", since "IN" events have a limit of 8 on that platform.

We didn't do the same work for the direct driver, so those boards won't properly wake from sleep, nor work for large number of input GPIO pins.

It shouldn't be hard to take inspiration from the changes for the matrix driver for this.