drm/amd/display: remove DC_FP_* wrapper from dml folder

FPU documentation states that developers must not use DC_FP_START/END
inside dml files, but use this macro to wrap calls to FPU functions in
dc folder (outside dml folder). Therefore, this patch removes DC_FP_*
wrappers from dml folder and wraps calls for these FPU operations
outside dml, as required.

Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>