drm/amd/display: changing sr exit latency

[Why]
Hardware team remeasured, need to update timings
to increase latency slightly and avoid intermittent
underflows.

[How]
sr exit latency update.

Signed-off-by: Martin Leung <martin.leung@amd.com>
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Qingqing Zhuo <Qingqing.Zhuo@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>