intel_idle: Support Intel Atom Processor C2000 Product Family

Support the "Intel(R) Atom(TM) Processor C2000 Product Family",
formerly code-named Avoton.  It is based on the next generation
Intel Atom processor architecture, formerly code-named Silvermont.

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>