staging/lustre: Get rid of an ugly statfs hack in lov_iocontrol

For some crazy reason ll_obd_statfs decided to decode async flag
passed from userspace and then pass it via a userspace pointer
argument to lov_iocontrol.
This patch moves flags decoding to lov_iocontrol where it belongs.

Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>