ACPI: add missing win8 OSI comment to blacklist

In my original patch[1] I wrote a comment describing the reason for
disabling Windows 2012 OSI mode for a group of machines, however, due to
unknown reasons (probably a conflict resolution mismatch), the comment
was dropped in 94fb9823 (ACPI: blacklist win8 OSI for buggy laptops).

Since Matthew Garrett is making a big deal out of the lack of comments
in a separate patch[2], it might make sense to re-introduce the missing
comment so that other patch is not blocked and users don't suffer.

[1] http://article.gmane.org/gmane.linux.acpi.devel/63427
[2] http://thread.gmane.org/gmane.linux.kernel/1572459



Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>