Named local labels shouldn't be used in LLVM because they might get
duplicated resulting in multiple symbol definitions and a compiler
error. Instead, use numeric labels.
This adjusts the timing for 120MHz as seen on atsamd51 boards. The
timing was kept as close as possible to the Cortex-M4 64MHz logic in
ws2812_m4_64m.go.
Tested: This works on ItsyBitsy-M4
Daniel Bridges
sago35
Ayke van Laethem
Jonathan Basseri