drm/i915/icl: fix step numbers in icl_display_core_init()

At some point the spec was changed and we never updated the numbers to
match it. Let's try once more to keep them in sync.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190404230426.15837-2-lucas.demarchi@intel.com