Initial import of Bitmine.ch A1 SPI driver

This initial driver was designed around an FPGA based
emulator board which provides 2 chained chips with 4
hashing engines each, running at 10% of the A1's
nominal speed.

Driver has been tested on RasPi.

Signed-off-by: Zefir Kurtisi <zefir.kurtisi@gmail.com>
A1: CoinCraft-Desk driver variant

The CoinCraft-Desk product includes up to 5 8-chip modules
that are accessed over a TCA9539 IO multiplexer.

This is the initial support for the CCD.
Merge pull request #551 from bitmine-ch/upstream.CCD

Upstream.ccd