ACPI: Get rid of 'unused variable' warning in acpi_ev_global_lock_handler()

Fix this warning :
  drivers/acpi/events/evmisc.c: In function `acpi_ev_global_lock_handler':
  drivers/acpi/events/evmisc.c:334: warning: unused variable `status'

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>