Revert "iscsi-target: Avoid IN_LOGOUT failure case for iser-target"

This reverts commit 72859d91.

The original patch was wrong, iscsit_close_connection() still needs
to release iscsi_conn during both normal + exception IN_LOGOUT status
with ib_isert enabled.

The original OOPs is due to completing conn_logout_comp early within
iscsit_close_connection(), causing isert_wait4logout() to complete
instead of waiting for iscsit_logout_post_handler_*() to be called.

Reported-by: Sagi Grimberg <sagig@mellanox.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Slava Shwartsman <valyushash@gmail.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>