libpayload: usb: dwc2: fix usb plug/unplug bug

Check device connect status while waiting for usb transfer complete
Avoid coreboot get stuck when usb device unplugged

BUG=chrome-os-partner:35525
TEST=None
BRANCH=None

Original-Change-Id: Id103501aa0d8b31b0b81bef773679c0fad79f689
Original-Signed-off-by: Yunzhi Li <lyz@rock-chips.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/292630
Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Original-Commit-Queue: Lin Huang <hl@rock-chips.com>
Original-Tested-by: Lin Huang <hl@rock-chips.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/292966
Original-Reviewed-by: David Hendricks <dhendrix@chromium.org>
Original-Tested-by: David Hendricks <dhendrix@chromium.org>
Original-Commit-Queue: David Hendricks <dhendrix@chromium.org>

Change-Id: I49396b74131dbfda505d9d3de5adbdc87eb92ce1
Signed-off-by: Yunzhi Li <lyz@rock-chips.com>
Reviewed-on: http://review.coreboot.org/11236
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/payloads/libpayload/drivers/usb/dwc2_private.h b/payloads/libpayload/drivers/usb/dwc2_private.h
index 5b1a547..73b6371 100644
--- a/payloads/libpayload/drivers/usb/dwc2_private.h
+++ b/payloads/libpayload/drivers/usb/dwc2_private.h
@@ -54,5 +54,6 @@
 	HCSTAT_NYET,
 	HCSTAT_UNKNOW,
 	HCSTAT_TIMEOUT,
+	HCSTAT_DISCONNECTED,
 } hcstat_t;
 #endif