target: Fix incorrect se_cmd assignment in core_tmr_drain_tmr_list

This patch fixes a bug in core_tmr_drain_tmr_list() where drain_tmr_list
was using the wrong se_tmr_req for cmd assignment due to a typo during the
LUN_RESET re-org.  This was resulting in general protection faults while
using the leftover bogus *tmr_p pointer from list_for_each_entry_safe().

Signed-off-by: Joern Engel <joern@logfs.org>
Cc: Joern Engel <joern@logfs.org>
Cc: stable@kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>