drm/i915/wm: Include ddb_y in skl_print_wm_changes() on pre-icl

drm/i915/wm: Include ddb_y in skl_print_wm_changes() on pre-icl

Pre-icl doesn't use a separate hardware plane for Y scanout,
and instead it's all handled magically by the hardware. We
do still need to allocate DDB space for the Y color plane
though (PLANE_NV12_BUF_CFG). Include that information in the
debugs so that we know where it ended up.

On icl+ the equivalent information is dumped as the hardware
Y plane's normal ddb allocation.

v2: Use prink field width for ddb_name alignment

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260319114034.7093-9-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>