Add support to mark sensors unavailable

This marks sensors unavailable when they respond
with nan, or when the available interface says
they are not available.

Tested:

ipmitool sensor list showed sensors as unavailable
SSB Temp         | na         | degrees C  | na    | na        | 0.000
  | 5.000     | 98.000    | 103.000   | na

Change-Id: I6a4f8ee14864e9d9330a58d83f71dde90cc23dbe
Signed-off-by: James Feist <james.feist@linux.intel.com>
1 file changed