drm/i915: Update plane ratio for icl+

According to bspec icl+ no longer need any extra cdclk guardband
for 64bpp formats. Make it so.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210330162416.18616-2-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>