Improvement of error matching necessary

[eldruin]

We have merged #71 which did the heavy-lifting for updating this to embedded-hal 1.0.0-alpha.6.
However, currently we are missing the extraction of information from the underlying nix/io errors in the embedded_hal::*::Error implementations so that they can be converted to a meaningful embedded_hal::*::ErrorKind.
At the moment, converting all errors to Other would render all drivers unable to act on things like i2c::NoAcknowledge.
For this one needs to dig a bit into the Linux kernel, and so on, though.

TODO:

• Add linux-i2cdev to e-h::i2c::ErrorKind mapping #75
• SPI
• Serial