scsi: target: qla2xxx: Convert to new submission API

target_submit_cmd() is now only for simple drivers that do their
own sync during shutdown and do not use target_stop_session().

tcm_qla2xxx uses target_stop_session() to sync session shutdown with LIO
core, so we use target_init_cmd()/target_submit_prep()/target_submit(),
because target_init_cmd() will detect the target_stop_session() call and
return an error.

Link: https://lore.kernel.org/r/20210227170006.5077-8-michael.christie@oracle.com


Cc: Nilesh Javali <njavali@marvell.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>