drm/amd/display: move FPU associated DSC code to DML folder

[Why & How]
As part of the FPU isolation work documented in
https://patchwork.freedesktop.org/series/93042/

, isolate code that uses
FPU in DSC to DML, where all FPU code should locate.

This change does not refactor any functions but move code around.

Cc: Christian König <christian.koenig@amd.com>
Cc: Hersen Wu <hersenxs.wu@amd.com>
Cc: Anson Jacob <Anson.Jacob@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Acked-by: Agustin Gutierrez <agustin.gutierrez@amd.com>
Tested-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>