drivers/arm: Implement acpi_fill_madt

drivers/arm: Implement acpi_fill_madt

Fill the MADT table in the GIC driver and armv8 CPU driver to
drop SoC specific code. While the GIC only needs devicetree
data, the CPU driver needs additional information stored in
the cpu_plat struct.

While on it update the only board making use of the existing
drivers and writing ACPI MADT in mainboard code.

TEST: Booted on QEMU sbsa-ref using GICV3 driver model generated MADT.
      Booted on QEMU raspb4 using GICV2 driver model generated MADT.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Simon Glass <sjg@chromium.org>