ACPI/cpuidle: bump maximum number of power states we support

ACPI/cpuidle: bump maximum number of power states we support

Commit 4c6cd64519 ("mwait_idle: Skylake Client Support") added a table
with 8 entries, which - together with C0 - rendered the current limit
too low. It should have been accompanied by an increase of the constant;
do this now. Don't bump by too much though, as there are a number of on-
stack arrays which are dimensioned by this constant.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wl@xen.org>
Release-acked-by: Juergen Gross <jgross@suse.com>