Revert "acpuclock-8x60: set default frequencies up to 1512(fast)"

This reverts commit 164527d085c43175e2ae7693910ee8070d46d281.
acpuclock-8x60: set default frequencies up to 1512(nom)

(fast is too optimistic on some 8x60's it seems)

I let the line concerning 1152 just not to get the unused warning.