Annotate disk params on blockdev_getmirrorstatus_multi

This is also related to the bug reported by Constantinos,
as we've only one getmirrorstatus_multi call in whole cmdlib, we just
annotate them while we are building the disk list.

Signed-off-by: René Nussbaumer <rn@google.com>
Reviewed-by: Agata Murawska <agatamurawska@google.com>