Changed BaseCPU::ProfileEvent's interval member to be of type Tick. This was done...

Changed BaseCPU::ProfileEvent's interval member to be of type Tick. This was done to be consistent with its
python type of a latency.  In addition, the multiple definitions of profile in the different cpu models caused
problems for intialization of the interval value. If a child class's profile value was defined, the parent
BaseCPU::ProfileEvent interval field would be initialized with a garbage value. The fix was to remove the
multiple redifitions of profile in the child CPU classes.