drm/i915: Start checking plane min size for the chroma plane

drm/i915: Start checking plane min size for the chroma plane

Currently we check the plane min size only for the Y plane.
Extend the check to the CbCr plane as well.

This will also allow us to remove the planar format check from
icl_plane_min_width() since the +2 on the CbCr plane is equivalent
to +4 on the Y plane. I suspect this approach actually models the
hardware issue more accurately.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20251009211313.30234-5-ville.syrjala@linux.intel.com
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>