ACPICA: Remove extra write for acpi_hw_clear_acpi_status

This function was writing an optional PM1B status register
twice.  The existing call to the low-level acpi_hw_register_write
automatically handles a possibly split PM1 A/B register.
ACPICA BZ 751.

http://www.acpica.org/bugzilla/show_bug.cgi?id=751

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>