drm/i915/display: Settle on "adl-x" in WA comments

Most of the places are using this format so lets consolidate it.

v2:
- split patch in two: display and non-display because of conflicts
between drm-intel-gt-next x drm-intel-next

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210713003854.143197-1-jose.souza@intel.com