Fix zvol_init error handling

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@prophetstor.com>

module/zfs/zvol.c

@@ -2367,6 +2367,7 @@ out_free:
 out_taskq:
 	taskq_destroy(zvol_taskq);
 out:
+	ida_destroy(&zvol_ida);
 	mutex_destroy(&zvol_state_lock);
 	list_destroy(&zvol_state_list);