drm/amd/display: CS_TFM_1D only applied post EOTF

[Why]
There's some unnecessary mem allocation for CS_TFM_ID. What's worse, it
depends on LUT size and since it's 4K for CS_TFM_1D, it is 16x bigger
than in regular case when it's actually needed. This leads to some
crashes in stress conditions.

[How]
Skip ramp combining designed for RGB256 and DXGI gamma with CS_TFM_1D.

Signed-off-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>