drm/amd/display: Use 4096 lut entries

Points in the DRM LUT are spaced linearly. Points in hardware are spaced
exponentially, with greater density towards 0. To maintain low-end
accuracy in hardware when sampling the DRM LUT, more points are needed.

However, X doesn't seem to play with legacy LUTs of such size.
Therefore, check for legacy lut when updating DC states, and update
accordingly.

v2: Use a macro for the maximum drm LUT value.

v3: Update commit to reflect that this does not map 1-1 to HW

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>