Minor potential improvements of USB robustness.

- atrf/fw/atspi/atspi.c (main): add a delay to give the host more time to
- atrf/fw/atspi/descr.c: we don't use EP1, so simplify the descriptors we
  send. Keep the EP1 descriptors around (commented out) in case  we need
  them later, e.g., for interrupts.

atrf/fw/atspi/atspi.c

@@ -90,8 +90,16 @@ static void init_io(void)
 
 void main(void)
 {
+	int i;
+
 	init_io();
 
+	/*
+	 * Make sure the host has enough time (2.5 us) to detect that we reset
+	 * our USB stack.
+	 */
+	for (i = 0; i != 10; i++);
+
 	usb_init();
 	ep0_init();