usb: hub: Send correct wValue to get hub descriptor of a USB 3.0 hub

usb: hub: Send correct wValue to get hub descriptor of a USB 3.0 hub

Testing a USB 3.0 hub by connecting it to the xHCI port on Intel
MinnowMax, when issuing 'get hub descriptor' to the hub, xHCI
reports a transfer event TRB with a completion code 6 which means
'Stall Error'.

In fact super speed USB hub descriptor type is 0x2a, not 0x29.
Sending correct SETUP packet to the hub makes it not stall anymore.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>