usb: fix some references for /proc/bus/usb

Since when we got rid of usbfs, the /proc/bus/usb is now
elsewhere. Fix references for it.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>