uboot-imx

PXA USB OHCI: "usb stop" implementation.

Some USB keys need to be switched off before loading the kernel
otherwise they can remain in an undefined status which prevents them
to be correctly recognized by the kernel.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Markus Klotzbuecher <mk@denx.de>