drm/amd/display: extract update stream allocation to link_hwss

[why]
Extract update stream allocation table into link hwss as part of the
link hwss refactor work.

Reviewed-by: George Shen <George.Shen@amd.com>
Reviewed-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>