* add gosched calls to UART
* add UART.flush() stubs for all supported architectures
* add comment un uart.go on flush functionality
* uart.writeByte as base of UART usage
* fix NXP having duplicate WriteByte
* fix writeByte not returning error on some platforms
* add flush method for fe310 device
* check for error in WriteByte call to writeByte
Do it all at once in preparation for Go 1.18 support.
To make this commit, I've simply modified the `fmt-check` Makefile
target to rewrite files instead of listing the differences. So this is a
fully mechanical change, it should not have introduced any errors.
Patricio Whittingslow
Yurii Soldak
sago35
Ayke van Laethem
Kenneth Bell
Fauchon
kenbell
GeoffThomas