ACPI: Verify device status after eject

ACPI spec states that the OS evaluates _STA after calling _EJ0
in order to verify if eject was successful.  Added a check to
verify if the enabled bit of the status value is cleared after
_EJ0.

Note, the present bit is not checked since some FW implementations
do not clear the present bit until the hardware is physically
removed.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>