drm/i915: Introduce intel_csc_matrix struct

Introduce a structure that can hold our CSC matrices. In there
we shall have the preoffsets, postoffsets, and coefficients,
all in platform specific format (at least for now).

We shall start by converting the ilk+ code to make use of
the new structure. chv will come later.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230329135002.3096-3-ville.syrjala@linux.intel.com


Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>