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>

drivers/gpu/drm/amd/display/dc/core/dc_link.c

@@ -754,8 +754,12 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
 			 * fail-safe mode
 			 */
 			if (dc_is_hdmi_signal(link->connector_signal) ||
-			    dc_is_dvi_signal(link->connector_signal))
+			    dc_is_dvi_signal(link->connector_signal)) {
+				if (prev_sink != NULL)
+					dc_sink_release(prev_sink);
+
 				return false;
+			}
 		default:
 			break;
 		}