threshold: use absolute value for D-Bus

Use the absolute value for threshold rather than percentage value.
This involves passing the total value from the metric collection so it
can be used in percentage calculation within health metric logic.

Change-Id: I46240aee54117c70637f9fbf882018f0eac520b2
Signed-off-by: Jagpal Singh Gill <paligill@gmail.com>
5 files changed