ACPICA: Clear PCIEXP_WAKE_STS when clearing ACPI events

When clearing status bits via acpi_hw_clear_acpi_status, also clear
the PCIEXP_WAKE_STS bit. Original change from Colin King.
ACPICA BZ 880.

http://www.acpica.org/bugzilla/show_bug.cgi?id=880
http://bugs.launchpad.net/bugs/613381

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>