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>
6 files changed