Decreases allowed based on all groups

For speed decreases to occur, all sensor groups involved with setting a
net decrease delta must be below their given t-control low values for
the associated zone. This handles the case where one or more sensor
groups' temperatures stabilize above their t-control low value, but one
or more other sensor groups' temperatures are below their t-control low
value which would result in speed decrease requests that could
eventually lead to fan speed oscillations.

Resolves openbmc/openbmc#2710

Change-Id: I382de5d3f9c3e631a332d49dfcb06e705ff6fc17
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
3 files changed