scsi: st: remove redundant pointer STbuffer

Pointer STbuffer is being assigned but is never used hence it is redundant
and can be removed.

Cleans up clang warning:
warning: variable 'STbuffer' set but not used [-Wunused-but-set-variable]
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Kai Mäkisara <kai.makisara@kolumbus.fi>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/st.c

@@ -828,11 +828,8 @@ static int st_flush_write_buffer(struct scsi_tape * STp)
 static int flush_buffer(struct scsi_tape *STp, int seek_next)
 {
 	int backspace, result;
-	struct st_buffer *STbuffer;
 	struct st_partstat *STps;
 
-	STbuffer = STp->buffer;
-
 	/*
 	 * If there was a bus reset, block further access
 	 * to this device.