Fix 'uptime' time correction attempt
Fix 'uptime' time correction attempt

When doing the attempt to correct time, the sense of comparison was
incorrect and the timestamp field was neglected.  Correct this
mistake and oversight.

Change-Id: Ia3ff187d0eaedcfea9f3b7d2c8f292162bb3bb50

openstack/pyghmi,stackforge/pyghmi,openstack/pyghmi