For iscsi read/write, expected_data_xfer_len
is 0, dxfer_dir is set to SPDK_SCSI_DIR_NONE.
But we can still have read/write op in SCSI layer.
This patch solves this issue.
Change-Id: I950e163fffb06fefaf8a913d1f6de29c96a52264
Signed-off-by: Ziye Yang <ziye.yang@intel.com>