drm/i915/hwconfig: Report no hwconfig support on ADL-N

ADL-N being a subplatform of ADL-P, it lacks support for hwconfig
table. Explicit check added to skip ADL-N.

Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220523075116.207677-1-balasubramani.vivekanandan@intel.com