drm/amd/display: change static screen wait frame_count for ips

[Why]
the original wait for 2 static frames before enter static screen
was not good enough for IPS-enabled case since enter/exit takes more time.

[How]
Changed logic for hardcoded wait frame values.

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Allen Pan <allen.pan@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>