iscsi-target: Fix processing of OOO commands

Fix two issues in OOO commands processing done at iscsit_attach_ooo_cmdsn.

Handle command serial numbers wrap around by using iscsi_sna_lt and not regular comparisson.

The routine iterates until it finds an entry whose serial number is greater than the serial number of
the new one, thus the new entry should be inserted before that entry and not after.

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>