USB: increase USB reset time

USB reset can be signaled by pulling low USB D+ for at least 10 ms,
according to the USB specification. This force a re-enumeration.
This time is increased to 20 ms to work with more USB HUBs.

Some SAM3S based board have external D+ pull-up mechanism (such as
SIMtrace) which needs to be used to pull D+ low.
This is a legacy mechanism from SAM7S history.
This mechanism is not required anymore on the SAM3S, and the qmod
does not use it. When the USB HAL is suspended, the transceiver is
disabled, causing D+ and D- to be pulled low. Then the HAL is activated
again. This is particularly required when DFU is started (and
enumerated), and after flashing the SAM3S switched to the main
application (without reset), so it can properly re-enumerate.

This board difference is now defined on the board header.

Change-Id: I9b58d8101c2fcf5595026b675728826af26127a3

firmware/libcommon/source/usb.c

@@ -2,6 +2,7 @@
  *         ATMEL Microcontroller Software Support
  * ----------------------------------------------------------------------------
  * Copyright (c) 2009, Atmel Corporation
+ * Copyright (c) 2018, sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de>
  *
  * All rights reserved.
  *
@@ -35,6 +36,7 @@
 #include "simtrace.h"
 #include "simtrace_usb.h"
 #include "utils.h"
+#include "USBD_HAL.h"
 
 #include <cciddriverdescriptors.h>
 #include <usb/common/dfu/usb_dfu.h>
@@ -576,11 +578,17 @@ void SIMtrace_USB_Initialize(void)
 {
 
 	/* Signal USB reset by disabling the pull-up on USB D+ for at least 10 ms */
+#ifdef PIN_USB_PULLUP
 	const Pin usb_dp_pullup = PIN_USB_PULLUP;
 	PIO_Configure(&usb_dp_pullup, 1);
 	PIO_Set(&usb_dp_pullup);
-	mdelay(15);
+#endif
+	USBD_HAL_Suspend();
+	mdelay(20);
+#ifdef PIN_USB_PULLUP
 	PIO_Clear(&usb_dp_pullup);
+#endif
+	USBD_HAL_Activate();
 
 	// Get std USB driver
 	USBDDriver *pUsbd = USBD_GetDriver();