tools/power/turbostat: Add Denverton support

Denverton is an Atom based micro server which shares the same
Goldmont architecture as Broxton. The available C-states on
Denverton is a subset of Broxton with only C1, C1e, and C6.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>