drm/amd/display: Fix MS/MP mismatches in dml21 for dcn401

[WHY]
Prefetch calculations did not guarantee that bandwidth required in
mode support was less than mode programming which can cause failures.

[HOW]
Fix bandwidth calculations to assume fixed times for OTO schedule,
and choose which schedule to use based on time to fetch pixel data.

Reviewed-by: Jun Lei <jun.lei@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>