* apa102: remove dead code
We can't store strings of hundreds of thousands of characters in RAM, so
this can't possibly have fired, historically. Pixbufs are still RAM
objects, so that's still out. With LFS, it would take a pathological
example to hit the required 400KB TSTRING.
* Add IRQ management functions
* ws2812: fill UART FIFOs with IRQs off
Refactor code to make the use of two fill loops less gross.
Nathaniel Wesley Filardo