drm/colorop: Add multiplier type

drm/colorop: Add multiplier type

This introduces a new drm_colorop_type: DRM_COLOROP_MULTIPLIER.

It's a simple multiplier to all pixel values. The value is
specified via a S31.32 fixed point provided via the
"MULTIPLIER" property.

Reviewed-by: Simon Ser <contact@emersion.fr>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Melissa Wen <mwen@igalia.com>
Reviewed-by: Sebastian Wick <sebastian.wick@redhat.com>
Signed-off-by: Simon Ser <contact@emersion.fr>
Link: https://patch.msgid.link/20251115000237.3561250-41-alex.hung@amd.com