sg: fix a warning in blk_rq_aligned() call

2nd argument of blk_rq_aligned() has changed to 'unsigned long' by
the previous commit 'block: fix an address space warning in blk-map.c'.
That commit neglected to update a user of that function.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

drivers/scsi/sg.c

@@ -1657,7 +1657,7 @@ static int sg_start_req(Sg_request *srp, unsigned char *cmd)
 	if (sg_allow_dio && hp->flags & SG_FLAG_DIRECT_IO &&
 	    dxfer_dir != SG_DXFER_UNKNOWN && !iov_count &&
 	    !sfp->parentdp->device->host->unchecked_isa_dma &&
-	    blk_rq_aligned(q, hp->dxferp, dxfer_len))
+	    blk_rq_aligned(q, (unsigned long)hp->dxferp, dxfer_len))
 		md = NULL;
 	else
 		md = &map_data;