drm/i915: Nuke force_min_cdclk_changed

Since we now have proper old and new cdclk state we no longer
need to keep this flag to indicate that the force min cdclk has
changed. Instead just check if the old vs. new value are different.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200714152626.380-4-ville.syrjala@linux.intel.com


Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>