platform/x86: think-lmi: Update password attribute comments

Add comments to clarify what the different password attributes
are (as requested).

Signed-off-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230601200552.4396-4-mpearson-lenovo@squebb.ca


Signed-off-by: Hans de Goede <hdegoede@redhat.com>