mraa-gpio-din: add cleanup on close

Required as nodejs will only lazily delete the node objects, and we may
race with the next user requesting the resources. ISR thread release.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Ivan Mikhaylov <ivan.mikhaylov@siemens.com>

hardware/intel/mraa-gpio-din.js

@@ -50,6 +50,8 @@ module.exports = function(RED) {
         }
         this.on('close', function() {
             node.x.isr(m.EDGE_BOTH, null);
+            node.x.isrExit();
+            node.x.close();
         });
     }
     RED.nodes.registerType("mraa-gpio-din", gpioDin);