xen: Port Xen bus driver from mini-os

Make required updates to run on u-boot and strip test code.

Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
7 files changed