Patch merged into coreboot/master: 4498f6a libpayload: usbhub: Don't clear PSC unless it was set

the following patch was just integrated into master:
commit 4498f6a6e57aa3bc1ed9449e3ad153b1a60c4eb6
Author: Julius Werner 
Date:   Tue Sep 3 16:44:15 2013 -0700

libpayload: usbhub: Don't clear PSC unless it was set

The current USB hub code always clears the port status change after
    checking it, regardless of whether it was set in the first place. Since
    this check runs on every poll, it might create a race condition where
    the port status changes right between the GET_PORT_STATUS and the
    CLEAR_FEATURE(C_PORT_CONNECT), thus clearing the statrus change flag
    before it was ever read. Let's add one extra if() to avoid that possible
    headache.

Change-Id: Idd46c2199dc6c240bd9ef068fbe70cccc88bac42
    Signed-off-by: Julius Werner 
    Reviewed-on: https://chromium-review.googlesource.com/168098
    (cherry picked from commit f7f6f008f701ab3e4a4f785032d8024d676e11cb)
    Signed-off-by: Isaac Christensen 
    Reviewed-on: http://review.coreboot.org/6617
    Tested-by: build bot (Jenkins)
    Reviewed-by: Patrick Georgi

See http://review.coreboot.org/6617 for details.

-gerrit