drm/amd/display: Update minimum stutter residency for DCN314 Z8

[Why]
Block periods that are too short as they have the potential to
currently cause hangs in other firmware components on the system.

[How]
Update the threshold, mostly targeting a block of 4k and downscaling.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>