Refactor part 1 of degamma/regamma programming.

End goal is to have source and output transfer function in
which dc can use to decide how to program the degamma
and regamma HW.

Gamma will be explicitly applied through
dc_update_surfaces_for_target.

Color module should build the logical curve with all
adjustments applied and pass enough information
for dc to program HW PWL.
Signed-off-by: Anthony Koo <anthony.koo@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>