[SCSI] st: remove unused st_buffer.in_use

I noticed that in_use in st_buffer is not used. The patch below
against 2.6.17-rc3 removes it, assuming there is no future use for it.
It was tested in a sparc SS20 with a DLT4000.
Signed-off-by: Martin Habets <errandir_news@mph.eclipse.co.uk>
Acked-by: Kai Mäkisara <kai.makisara@kolumbus.fi>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/st.c

@@ -3599,7 +3599,6 @@ static struct st_buffer *
 	tb->use_sg = max_sg;
 	tb->frp = (struct st_buf_fragment *)(&(tb->sg[0]) + max_sg);
 
-	tb->in_use = 1;
 	tb->dma = need_dma;
 	tb->buffer_size = got;
 

drivers/scsi/st.h

@@ -31,7 +31,6 @@ struct st_request {
 
 /* The tape buffer descriptor. */
 struct st_buffer {
-	unsigned char in_use;
 	unsigned char dma;	/* DMA-able buffer */
 	unsigned char do_dio;   /* direct i/o set up? */
 	int buffer_size;