acpi: use 64-bit addresses in FADT table

Fields X_FIRMWAE_CTRL and X_DSDT must be 64bit wide. Convert pointers to
to uintptr_t to fill these.

If field X_FIRMWARE_CTRL is filled, field FIRMWARE must be ignored. If
field X_DSDT is filled, field DSDT must be ignored. We should not fill
unused fields.

See the field definitions in chapter "5.2.9 Fixed ACPI Description Table
(FADT)" of the ACPI Specification 6.5.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>