drm/amd/display: Set stream_count to 0 when dc_resource_state_destruct.

[Why]
When hardware need to be reset, driver need to reset stream objects but
dc_resource_state_destruct function omit resetting stream_count. It will
lead page fault if some logic will touch stream object.

[How]
Set stream_count to 0 when dc_resource_state_destruct.

Signed-off-by: Paul Wu <paul.wu@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Wayne Lin <Wayne.Lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>