LU-7623 lov: Get rid of an ugly statfs hack in lov_iocontrol

LU-7623 lov: 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.

Change-Id: I1b54e778d60b878fc3fc463c256aad360b2cab21
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: http://review.whamcloud.com/17780
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>