Add removal_type in structure acpi_device for hot removal.

ACPI_BUS_REMOVAL_EJECT is used for ACPI device hot removal.
Only one parameter is allowed in .remove method due to driver model.
So removal_type is added to indicate different removal type.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>