board: Introduce xenguest_arm64 board

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: Andrii Anisov <andrii_anisov@epam.com>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
diff --git a/board/xen/xenguest_arm64/MAINTAINERS b/board/xen/xenguest_arm64/MAINTAINERS
new file mode 100644
index 0000000..787e9e0
--- /dev/null
+++ b/board/xen/xenguest_arm64/MAINTAINERS
@@ -0,0 +1,7 @@
+XEN GUEST FOR ARM64
+M:	Andrii Anisov <andrii_anisov@epam.com>
+S:	Maintained
+F:	board/xen/xenguest_arm64/
+F:	doc/board/xen/
+F:	include/configs/xenguest_arm64.h
+F:	configs/xenguest_arm64_defconfig