drm/amd/display: program output tf when required

[Description]
Output transfer function must be programmed per pipe as part of a front end
update when the plane changes, or output transfer function changes for a
given plane.

Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Dillon Varone <Dillon.Varone@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>