Tommy Hilfiger Shares Tumble on Probe  NEW YORK (Reuters) - Shares of Tommy Hilfiger Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=TOM.N target=/stocks/quickinfo/fullquote"&gt;TOM.N&lt;/A&gt;  fell as much as 26 percent on Monday after a federal grand jury  subpoenaed documents on commissions paid to a foreign  subsidiary of the clothing maker.