[flashrom] Add support for WCH CH341A as an SPI programmer.

[Stefan Tauner]

Hi,

I am writing to you because you were interested in CH341A support in
flashrom in the past. I am happy to announce that we have merged the
respective patch in r1921 and it should work fine on any operating
system that supports libusb1. It will be included in the upcoming 0.9.9
release of flashrom as well.