drm/amd/display: Re-arrange FPU code structure for dcn2x

[ Upstream commit ee373411 ]

[Why]
Current FPU code for DCN2x is located under dml/dcn2x.
This is not aligned with DC's general source tree
structure.

[How]
Move FPU code for DCN2x to dml/dcn20.

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Signed-off-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Stable-dep-of: e63e35f0 ("drm/amd/display: Increase frame-larger-than for all display_mode_vba files")
Signed-off-by: Sasha Levin <sashal@kernel.org>