Add tach sensor functional delay

Add ability to define a delay to marking a tach sensor as functional
when it transitions from a nonfunctional state. Essentially this gives
the option to wait a given amount of time that a tach sensor must be
within the allowed deviation before being updated to functional.

Default functional delay = 0 seconds

Tested: Current fan definition values function the same

Change-Id: I58bf70d2335e27c06037b755cbee8dae81528a5a
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/monitor/example/monitor.yaml b/monitor/example/monitor.yaml
index 4819d12..7676fde 100644
--- a/monitor/example/monitor.yaml
+++ b/monitor/example/monitor.yaml
@@ -7,6 +7,9 @@
 #fans:
 # - inventory:
 #    [The system inventory location for the fan]
+#  functional_delay:
+#    [Delay (in secs) before a fan is marked functional after returning
+#     within the allowed deviation]
 #  allowed_out_of_range_time:
 #    [Time (in secs) actual speed can be outside of deviation of
 #     target speed]
@@ -53,6 +56,7 @@
 #Example entries for 1 fan system:
 #fans:
 #  - inventory: /system/chassis/motherboard/fan0
+#    functional_delay: 5
 #    allowed_out_of_range_time: 15
 #    deviation: 15
 #    num_sensors_nonfunc_for_fan_nonfunc: 1