acpi: arm/virt: madt: use build_append_int_noprefix() API to compose MADT table

Drop usage of packed structures and explicit endian conversions
when building MADT table for arm/x86 and use endian agnostic
build_append_int_noprefix() API to build it.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-Id: <20210924122802.1455362-26-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>