drm/i915: Nuke stale plane cdclk ratio FIXMEs

The plane ratio stuff got implemented in
commit bb6ae9e6 ("drm/i915: Allow planes to
declare their minimum acceptable cdclk") so these
FIXMEs have no business being here.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220916165206.1499-1-ville.syrjala@linux.intel.com


Reviewed-by: Luca Coelho <luciano.coelho@intel.com>