drm/amd/display: Fix memory leak caused by missed dc_sink_release

[Why]
There is currently an intermittent hang from a memory leak in
DTN stress testing. It is caused by unfreed memory during driver
disable.

[How]
Do a dc_sink_release in the case that skips it incorrectly.

Signed-off-by: SivapiriyanKumarasamy <sivapiriyan.kumarasamy@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>