python-spidev: new package

Python module for interfacing with SPI devices from user space via the
spidev linux kernel driver.

[Thomas: fix <pkg>_LICENSE_FILES.]

Cc: Yegor Yefremov <yegorslists@googlemail.com>
Reviewed-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>