serial: sunsab: Fix error handling in sunsab_init()

The sunsab_init() returns the platform_driver_register() directly without
checking its return value, if platform_driver_register() failed, the
allocated sunsab_ports is leaked.
Fix by free sunsab_ports and set it to NULL when platform_driver_register()
failed.

Fixes: c4d37215a8 ("[SERIAL] sunsab: Convert to of_driver framework.")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Link: https://lore.kernel.org/r/20221123061212.52593-1-yuancan@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sunsab.c

@@ -1131,7 +1131,13 @@ static int __init sunsab_init(void)
 		}
 	}
 
-	return platform_driver_register(&sab_driver);
+	err = platform_driver_register(&sab_driver);
+	if (err) {
+		kfree(sunsab_ports);
+		sunsab_ports = NULL;
+	}
+
+	return err;
 }
 
 static void __exit sunsab_exit(void)