wspoon: Add critical thresholds for fan speeds

The values are just outside of the allowed margins of the
fan floor and max speed values.

Tested: Test that the thresholds show up in the web UI
        and that the web UI shows when they have been
        crossed.

Resolves openbmc/openbmc#3114

Change-Id: I6420252d98b974921d6858dbecb3b52f5a8c646a
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
2 files changed