monitor: Add delay for host control

Some OpenBMC platforms use dbus-sensor and entity-manager to create
the fan sensors. In those systems, phosphor-fan-monitor starts before
the fan sensors are created during BMC boot up. phosphor-fan-monitor
is designed to shutdown the host when there is no fan tach sensors which
is not desirable in this case. This patch supports a package
configuration option delay-host-control to add a desired delay before
phosphor-fan-monitor turns off host. This can be configured to match
with each system timing.

Signed-off-by: Chau Ly <chaul@amperecomputing.com>
Change-Id: I63cd85eb5e6cb04069ce7b4c21c2f4621d243502
3 files changed