MYSQL cuenta de cuenta?

Puede envolver su consulta dentro de otra:

SELECT
    cnt      AS page_visits
  , COUNT(*) AS number_of_visitors
FROM
    ( SELECT 
          COUNT(*) AS cnt                --- use: COUNT(DISTINCT page_id)
                                         --- for a different count
      FROM vislog 
      GROUP BY visid
   ) AS grp
GROUP BY cnt 
ORDER BY number_of_visitors ;

o (supongo que esto tiene más sentido para pasar los números a un gráfico), eliminar ORDER BY que es lo mismo que poner:

ORDER BY cnt ;