drm/amd/display: Fix urgent latency override for DCN32/DCN321

[Why]
The urgent latency override is useful when debugging issues
relating to underflow.

Current overridden variable is not correct and has no effect
on DCN3.2 and DCN3.21 DML calculations.

[How]
For DCN3.2 and DCN3.21, override the correct urgent latency
variable when bounding box override is present.

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Reviewed-by: Nevenko Stupar <Nevenko.Stupar@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: George Shen <george.shen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>