Introduce a minimal Xen guest board running as a virtual
machine under Xen Project's hypervisor [1], [2].

Part of the code is ported from Xen mini-os and also uses
work initially done by different authors from NXP: please see
relevant files for their copyrights.

[1] https://xenbits.xen.org
[2] https://wiki.xenproject.org/Signed-off-by: NAndrii Anisov <andrii_anisov@epam.com>
Signed-off-by: NOleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: NAnastasiia Lukianenko <anastasiia_lukianenko@epam.com>