[SCSI] fix up request buffer reference in various scsi drivers

Various scsi drivers use scsi_cmnd.buffer and scsi_cmnd.bufflen in their
queuecommand functions.  Those fields are internal storage for the
midlayer only and are used to restore the original payload after
request_buffer and request_bufflen have been overwritten for EH.  Using
the buffer and bufflen fields means they do very broken things in error
handling.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/ips.c b/drivers/scsi/ips.c
index a4c0b04..350c08c 100644
--- a/drivers/scsi/ips.c
+++ b/drivers/scsi/ips.c
@@ -4364,7 +4364,7 @@
 
 	METHOD_TRACE("ips_rdcap", 1);
 
-	if (scb->scsi_cmd->bufflen < 8)
+	if (scb->scsi_cmd->request_bufflen < 8)
 		return (0);
 
 	cap.lba =