drm/amd/display: Query all entries in assignment table during updates.

[Why]
Stream ordering and count can vary from one state to the next. Only
checking a subset of entries in the encoder assignment table can lead to
invalid encoder assignments.

[How]
Check all entries in encoder assignment table when querying it.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>