drm/i915/tgl: Fix REVID macros for TGL to fetch correct stepping

drm/i915/tgl: Fix REVID macros for TGL to fetch correct stepping

Fix TGL REVID macros to fetch correct display/gt stepping based
on SOC rev id from INTEL_REVID() macro. Previously, we were just
returning the first element of the revid array instead of using
the correct index based on SOC rev id.

Fixes: c33298cb34f5 ("drm/i915/tgl: Fix stepping WA matching")
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Aditya Swarup <aditya.swarup@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201203072359.156682-1-aditya.swarup@intel.com