usb: ci_udc: implement dfu_usb_get_reset

This allows the USB code to determine whether a USB bus reset was issued,
which in turn allows the code to differentiate between a detach (return
to shell prompt) and a board reset/reboot request.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/drivers/usb/gadget/ci_udc.c b/drivers/usb/gadget/ci_udc.c
index 4cd19c3..2572b34 100644
--- a/drivers/usb/gadget/ci_udc.c
+++ b/drivers/usb/gadget/ci_udc.c
@@ -919,3 +919,10 @@
 
 	return 0;
 }
+
+bool dfu_usb_get_reset(void)
+{
+	struct ci_udc *udc = (struct ci_udc *)controller.ctrl->hcor;
+
+	return !!(readl(&udc->usbsts) & STS_URI);
+}