libpayload: usb: Add support for SuperSpeed hubs

This patch adds support for the SuperSpeed half of USB 3.0 hubs, which
previously prevented SuperSpeed devices behind those hubs from working.

BRANCH=None
BUG=chrome-os-partner:39877
TEST=Played around with multiple hubs and devices on Oak and Falco, can
no longer find a combination that doesn't work.

Change-Id: I20815be95769e33d399b7ad91c3020687234e059
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 3db96ece20d2304e7f6f6aa333cf114037c48a3e
Original-Change-Id: I2dd6c9c3607a24a7d78c308911e3d254d5f8d91d
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/284577
Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Tested-by: chunfeng yun <chunfeng.yun@mediatek.com>
Reviewed-on: http://review.coreboot.org/10958
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/payloads/libpayload/drivers/usb/xhci_debug.c b/payloads/libpayload/drivers/usb/xhci_debug.c
index d50f6db..f8d2309 100644
--- a/payloads/libpayload/drivers/usb/xhci_debug.c
+++ b/payloads/libpayload/drivers/usb/xhci_debug.c
@@ -80,8 +80,8 @@
 	int i;
 	if (ctx_mask & 1)
 		xhci_dump_slotctx(dc->slot);
-	for (i = 0; i < SC_GET(CTXENT, dc->slot); ++i) {
-		if (ctx_mask & (2 << i))
+	for (i = 1; i <= SC_GET(CTXENT, dc->slot); ++i) {
+		if (ctx_mask & (1 << i))
 			xhci_dump_epctx(dc->ep[i]);
 	}
 }