drm/amd/display: Remove Duplicate Prefetch Parameter

drm/amd/display: Remove Duplicate Prefetch Parameter

[Why/How]
UrgLatency value is passed in twice to the prefetch calculations.
Once through the UrgentLatency term and once through the Turg term.
Only Turg is used in the prefetch calculation so remove the unused UrgentLatency parameter

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Zheng, Austin <Austin.Zheng@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>