drm/i915/guc: ADL-N should use the same GuC FW as ADL-S

The only difference between the ADL S and P GuC FWs is the HWConfig
support. ADL-N does not support HWConfig, so we should use the same
binary as ADL-S, otherwise the GuC might attempt to fetch a config
table that does not exist. ADL-N is internally identified as an ADL-P,
so we need to special-case it in the FW selection code.

Fixes: 7e28d0b2

 ("drm/i915/adl-n: Enable ADL-N platform")
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Tejas Upadhyay <tejas.upadhyay@intel.com>
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220621233005.3952293-1-daniele.ceraolospurio@intel.com