drm/amd/display: Unblank hubp based on plane visibility

[WHY]
DCN10 uses plane visibility to determine when to unblank HUBP; there is
no reason DCN20+ should not do the same.

[HOW]
In addition to changing the check in HWSEQ, we must change
is_pipe_tree_visible so that it checks ODM pipe topologies as well as
MPC. Since we're now checking both ODM and MPC topologies, the helper
function names have been changed to reference "parent" and "child"
instead of "top" and "bottom".

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Wesley Chalmers <Wesley.Chalmers@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>