ACPI: use _STA bit names rather than 0x0F

Be explicit about what "device->status = 0x0F" really means.

syntax only.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>