intel_idle: Add AlderLake-N support

Similar to the other other AlderLake platforms, the C1 and C1E states on
ADL-N are mutually exclusive. Only one of them can be enabled at a time.

C1E is preferred on ADL-N for better energy efficiency.

C6S is also supported on this platform. Its latency is far bigger than
C6, but really close to C8 (PC8), thus it is not exposed as a separate
state.

Suggested-by: Baieswara Reddy Sagili <baieswara.reddy.sagili@intel.com>
Suggested-by: Vinay Kumar <vinay.kumar@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>