[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/seagate.c b/drivers/scsi/seagate.c
index 3f312a8..2679ea8b 100644
--- a/drivers/scsi/seagate.c
+++ b/drivers/scsi/seagate.c
@@ -1002,7 +1002,7 @@
 			}
 #endif
 
-			buffer = (struct scatterlist *) SCint->buffer;
+			buffer = (struct scatterlist *) SCint->request_buffer;
 			len = buffer->length;
 			data = page_address(buffer->page) + buffer->offset;
 		} else {