The PnPID for a device may not be on the immediate parent, so search up the
device tree until we find one.
X.Org Bug 75513 <http://bugs.freedesktop.org/show_bug.cgi?id=75513>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Tested-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
(cherry picked from commit 795066477e)