The SoftSPI constructor is now used soley to create SoftSPI instances, it
can no longer delegate to create a hardware-based SPI instance.
Signed-off-by: Damien George <damien@micropython.org>
Because otherwise the function can return with data still waiting to be
clocked out, and CS might then be disabled before the SPI transaction is
complete. Fixes issue #3487.
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.