This avoids any sysfs-related deadlock (or lockdep warning), such
as reported at http://lkml.org/lkml/2010/1/17/88 .
Reported-by: Ming Lei <tom.leiming@gmail.com>
Tested-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>