drm/i915/cdclk: Extract intel_cdclk_update_crtc_min_cdclk()

drm/i915/cdclk: Extract intel_cdclk_update_crtc_min_cdclk()

Hide the cdclk state details better by providing a helper
(intel_cdclk_update_crtc_min_cdclk()) by which the crtc code
can inform the cdclk code about a new per-pipe min_cdclk value.

Note that this is currently being called once per-plane, but
it'll be changed to be just a single call for the whole pipe
later.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250923171943.7319-11-ville.syrjala@linux.intel.com
Reviewed-by: Mika Kahola <mika.kahola@intel.com>