commit 72949ef (iscsid: set PR_SET_IO_FLUSHER) set the iscsid's
PR_SET_IO_FLUSHER flag to avoid deadlock. While we do not need
to set this flag when scanning host.
If this flag is set for scanning thread, we may lost devices
reported by target because of memory allocation failure.
Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
