Revert "ltunify: make fkeyswap default action status"

This reverts commit 0b12a96aa7209ac2e4b3a5bb7b96aff1e116474b.

The keyboard register is not too generic.
Revert "ltunify: implement fkeyswap command"

This reverts commit 7f870c0ca5f27827a411d1ee7a11ef5103432413.

The keyboard register is not too generic
Fix logic flaw in array bounds

Index 0xFF needs an array of size 0x100... This error was caught with
Address Sanitizer while trying to iterate through all registers 0x00..0xFF.
registers.txt: document all registers for K800 and M525