drm/i915: remove unused ADLS_REVID_* macros

It's the adls_revid_step_tbl array indexes that matter.

Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/996274d28cf939186a748b4714872b1c31b23adb.1615211711.git.jani.nikula@intel.com