drm/i915: Introduce scaling filter related registers and bit fields

Introduce scaler registers and bit fields needed to configure the
scaling filter in prgrammed mode and configure scaling filter
coefficients.

changes since v3:
* None
changes since v2:
* Change macro names to CNL_* and  use +(set)*8 instead of adding
  another trip through _PICK_EVEN (Ville).
changes since v1:
* None
changes since RFC:
* Parametrize scaler coeffient macros by 'set' (Ville)

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201020161427.6941-3-pankaj.laxminarayan.bharadiya@intel.com