Added isochronous transfer

usb/iso.c

@@ -0,0 +1,9 @@
+#include <libusb-1.0/libusb.h>
+
+void _callback(struct libusb_transfer *xfer) {
+	iso_callback(xfer->user_data);
+}
+
+libusb_transfer_cb_fn callback() {
+  return &_callback;
+}