Add enableVbus function

Author: sebromero

libraries/USBHOST/src/USBHost.cpp

@@ -3,6 +3,10 @@
 
 static rtos::Thread t(osPriorityHigh);
 
+void USBHost::supplyPowerOnVBUS(bool enable){
+  mbed::DigitalOut otg(PJ_6, enable ? 0 : 1);
+}
+
 void USBHost::InternalTask() {
   while (1) {
     tusbh_msg_loop(mq);

libraries/USBHOST/src/USBHost.h

@@ -26,6 +26,12 @@ class USBHost {
 		return _hs;
 	};
 
+	/**
+	 * Allows to provide power to USB devices on VBUS when powered through VIN.
+	 * @param enable A flag to indicate whether power is supplied on VBUS.
+	*/
+	void supplyPowerOnVBUS(bool enable);
+
 private:
 
 	void InternalTask();