drm/amd/display: Move predict pipe to dml fpu folder

The function dcn32_predict_pipe_split uses FPU operations. This commit
moves this function to the dcn32_fpu file, and we ensure that we only
invoke it under the kernel_fpu protection.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>