thunderbolt: Do not report errors if on-board retimers are found

Currently we return an error even if on-board retimers are found and
that's not expected. Fix this to return an error only if there was one
and 0 otherwise.

Fixes: 1e56c88a ("thunderbolt: Runtime resume USB4 port when retimers are scanned")
Cc: stable@vger.kernel.org
Signed-off-by: Utkarsh Patel <utkarsh.h.patel@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/retimer.c

@@ -471,10 +471,9 @@ int tb_retimer_scan(struct tb_port *port, bool add)
 			break;
 	}
 
-	if (!last_idx) {
-		ret = 0;
+	ret = 0;
+	if (!last_idx)
 		goto out;
-	}
 
 	/* Add on-board retimers if they do not exist already */
 	for (i = 1; i <= last_idx; i++) {