x86: acpi: Clean up table header revisions

x86: acpi: Clean up table header revisions

The comment of initializing table header revision says:

    /* ACPI 1.0/2.0: 1, ACPI 3.0: 2, ACPI 4.0: 3 */

which might mislead it may increase per ACPI spec revision.
However this is not the case. It's actually a fixed number
as defined in ACPI spec, and in the laest ACPI spec 6.1,
some table header revisions are still 1. Clean these up.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>