Map plane blend properties to DPP blend gamma. Plane blend is a
post-3D LUT curve that linearizes color space for blending. It may be
defined by a user-blob LUT and/or predefined transfer function. As
hardcoded curve (ROM) is not supported on blend gamma, we use AMD color
module to fill parameters when setting non-linear TF with empty LUT.

v2:
- rename DRM TFs to AMDGPU TFs
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Joshua Ashton <joshua@froggi.es>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>