This prefix isn't actually used and only adds noise, so remove it.
It may have been useful on Linux that makes a distinction between
/dev/ttyACM* and /dev/ttyUSB* but it isn't now. Also, it's unlikely that
the same vid/pid pair will be shared between an acm and usb driver
anyway.
Instead of specifying explicit commands, most of these commands have
been replaced by more specific properties.
This is work that will be necessary for an eventual -programmer flag to
the compiler, with which it is possible to select which programmer to
use to flash or debug a chip. That's not very useful for boards that
already include a programmer or bootloader for that purpose, but is very
useful for novel boards or single-purpose boards that are not already
included in TinyGo.
