tcm_fc: Fix ft_send_tm LUN lookup OOPs

This patch fixes a bug in ft_send_tm() that was incorrectly calling
ft_get_lun_for_cmd() -> transport_get_lun_for_cmd(), instead of using
transport_get_lun_for_tmr() for the proper struct se_lun lookup
that was triggering an OOPs in the se_cmd->tmr_req failure path.

This patch fixes the issue by re-arranging the codepath where
transport_get_lun_for_tmr() is called after tmr request is allocated and
made it available as part of se_cmd.

It also drops the now unnecessary ft_get_lun_for_cmd() unpacking code, and
uses scsilun_to_int() directly ahead of transport_get_lun_for_cmd() and
transport_get_lun_for_tmr() usage.

Signed-off-by: Patil, Kiran <kiran.patil@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>