drm/i915: Relocate skl_get_pfit_config()

Move skl_get_pfit_config() next to the other skl+ scaler code
and rename it to skl_scaler_get_config() so that it has a consistnet
namespace.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230418175528.13117-5-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

drm/i915: Relocate intel_atomic_setup_scalers()

Move intel_atomic_setup_scalers() next to the other scaler
code in skl_scaler.c.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230418175528.13117-4-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

drm/i915: refactor skylake scaler code into new file.

This moves the code from various places and consolidates it
into one new file.

v2:
- rename skl_program_plane -> skl_program_plane_scaler (Ville)
- also move skl_pfit_enable, and consequently make some skl_scaler_*
functions static to skl_scaler.c (Ville)

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/2fa703ffc7b96a41c392fd5ebbd2e6e4ffb6fb05.1612536383.git.jani.nikula@intel.com