ACPICA: always disable GPE when requested

acpi_ev_disable_gpe() has an optimization where it doesn't disable
a GPE that it "doesn't have to".  Unfortunately, it can get tricked
by AML that scribbles on register state behind its back.  So when asked
to disable a GPE, simply do it -- a redundant register write
in the common case is a fair price to pay to be bomb-proof
for the rare cases.

http://bugzilla.kernel.org/show_bug.cgi?id=6217

Signed-off-by: Damián Viano <des@debian.org>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>