Staging: IndustryPack bus for the Linux Kernel

Add IndustryPack bus support for the Linux Kernel.

This is a virtual bus that allows to perform all the operations between
carrier and mezzanine boards.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>