drm/i915/casf: Move the casf state to better place

drm/i915/casf: Move the casf state to better place

The casf state is placed inside the 'hw' state for some reason.
That is only really meant for things we have to duplicate from
the uapi state. The rest can live on its own in our actual state.

And since casf is just one aspect of the pfit/pipe scaler the
proper place for it seems to be under pch_pfit.

Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>
Reviewed-by: Nemesa Garg <nemesa.garg@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260407175244.19654-4-ville.syrjala@linux.intel.com