control: Associate identifier with target holds

Create a zone method that associates a unique identifier to a target
hold so that if more than one hold exists, the highest target is always
used between all actions that could have set a target hold on the zone.

Change-Id: I7699769a2e271c8a63a0a0a05aef6b0888ce180a
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
4 files changed