Patch merged into coreboot/master: 59c020a libpayload: fix use-after-free in usb_exit()

the following patch was just integrated into master:
commit 59c020ab15fcc090e0605df1e17f41ffa861b153
Author: Mathias Krause 
Date:   Sun Mar 24 19:40:02 2013 +0100

libpayload: fix use-after-free in usb_exit()

The controller's shutdown function free()s the controller structure so
    we shouldn't access it any more after calling shutdown.

As all controllers detach themself, i.e. unchain themself from usb_hcs,
    just keep iterating over usb_hcs until it's NULL.

Change-Id: Ie85caba0f685494c3fe04c550a5a14bc4158a94e
    Signed-off-by: Mathias Krause 
    Reviewed-on: http://review.coreboot.org/2900
    Reviewed-by: Paul Menzel 
    Tested-by: build bot (Jenkins)
    Reviewed-by: Anton Kochkov

Build-Tested: build bot (Jenkins) at Mon Mar 25 12:47:17 2013, giving +1
Reviewed-By: Anton Kochkov  at Mon Mar 25 15:34:13 2013, giving +2
See http://review.coreboot.org/2900 for details.

-gerrit