sysfs: fix the rest of the kernel so if an attribute doesn't
       implement show or store method read/write will return
       -EIO instead of 0 or -EINVAL or -EPERM.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>