LU-7593 target: take ted_lcd_lock after transaction started

LU-7593 target: take ted_lcd_lock after transaction started

Otherwise the thread1 may be blocked during the transaction start
in tgt_client_data_update() with 'ted_lcd_lock' held because another
thread2 may be blocked by such lock in tgt_txn_stop_cb() but with
transaction handle started. That is deadlock.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: Id623d171e43beaa54ae4a9718fb4dc52c474df01
Reviewed-on: http://review.whamcloud.com/23129
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Jenkins
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>