drm/i915: Tidy workaround definitions

Removal of the DG2 pre-production workarounds has left duplicate
condition blocks in a couple places, as well as some inconsistent
platform ordering.  Reshuffle and consolidate some of the workarounds to
reduce the number of condition blocks and to more consistently follow
the "newest platform first" convention.  Code movement only; no
functional change.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Matt Atwood <matthew.s.atwood@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230816214201.534095-11-matthew.d.roper@intel.com