[SCSI] More buffer->request_buffer changes

Seem like quite a few splipped through the cracks.  Here's a patch to
update all references I could find:

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/wd33c93.c b/drivers/scsi/wd33c93.c
index 680f38a..2083454 100644
--- a/drivers/scsi/wd33c93.c
+++ b/drivers/scsi/wd33c93.c
@@ -373,7 +373,7 @@
  */
 
 	if (cmd->use_sg) {
-		cmd->SCp.buffer = (struct scatterlist *) cmd->buffer;
+		cmd->SCp.buffer = (struct scatterlist *) cmd->request_buffer;
 		cmd->SCp.buffers_residual = cmd->use_sg - 1;
 		cmd->SCp.ptr = page_address(cmd->SCp.buffer->page) +
 		    cmd->SCp.buffer->offset;