This is so the user of libpayload can attach data to the device which it can
retrieve when the device is referred to later, for instance in usbdisk_remove.
Otherwise, there's no direct connection from the usbdev_t structure to any
bookkeeping in the host firmware.
Change-Id: I36fe693b0dcd2098e359c26744e376e73bd3a723
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: http://review.coreboot.org/2513
Tested-by: build bot (Jenkins)
Reviewed-by: Nico Huber <nico.huber@secunet.com>