[SCSI] fix panic when ejecting ieee1394 ipod

The scsi_library routines don't correctly set DMA_NONE when
req->data_len is zero (instead they check the command type first, so
if it's write, we end up with req->data_len == 0 and direction as
DMA_TO_DEVICE which confuses some drivers)

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_lib.c

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 4afef5c..0978887 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1215,12 +1215,12 @@
 		} else {
 			memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
 			cmd->cmd_len = req->cmd_len;
-			if (rq_data_dir(req) == WRITE)
-				cmd->sc_data_direction = DMA_TO_DEVICE;
-			else if (req->data_len)
-				cmd->sc_data_direction = DMA_FROM_DEVICE;
-			else
+			if (!req->data_len)
 				cmd->sc_data_direction = DMA_NONE;
+			else if (rq_data_dir(req) == WRITE)
+				cmd->sc_data_direction = DMA_TO_DEVICE;
+			else
+				cmd->sc_data_direction = DMA_FROM_DEVICE;
 			
 			cmd->transfersize = req->data_len;
 			cmd->allowed = 3;