scsi: qla2xxx: Remove qla_tgt_cmd.data_work and qla_tgt_cmd.data_work_free

The 'data_work' and 'data_work_free' member variables are set but never
used. Hence remove both member variables. See also commit 6bcbb317
("qla2xxx: Fix incorrect tcm_qla2xxx_free_cmd use during TMR ABORT (v2)").

Cc: Himanshu Madhani <hmadhani@marvell.com>
Cc: Giridhar Malavali <gmalavali@marvell.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>