[usb] Reset endpoints before setting them up.

This fixes an enumaration bug when plugging, un-plugging and re-plugging
the calculator.

Change-Id: Ifbb4386b46b7492ce2b833e9e4755fd3cfefc708

ion/src/device/usb.cpp

@@ -214,6 +214,7 @@ void poll() {
     /* Handle USB RESET. */
     OTG.GINTSTS()->setENUMDNE(true); //Clear the ENUMDNE bit.
     usb_set_address(0);
+    usb_endpoints_reset();
     usb_endpoint_setup();
     return;
   }