Decrease severity of 'Disabled' presence

This is generally used to indicate the benign configuration
choice of disabling some present device.  For example, a
server with a built in network device disabled in favor of
an add-in option.

Change-Id: I1cf9f4feccf7ec022cca7ce7909093b16807244c

pyghmi/ipmi/private/constants.py

@@ -1055,7 +1055,7 @@ sensor_type_offsets = {
         },
         2: {
             'desc': 'Disabled',
-            'severity': const.Health.Warning,
+            'severity': const.Health.Ok,
         },
     },
     0x27: {  # LAN heartbeat