When booting OvmfXen, the ACPI interface for shutdown/reset might not
be available, instead use the hypercall interface.
While it's probably possible to use the hypercall in all cases, we
keep using the same interface while it still possible. That is ACPI on
HVM guest, and fallback to hypercall on PVH guest.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Jason Andryuk <jason.andryuk@amd.com>