Fannie Mae in Deal to Up Capital  WASHINGTON (Reuters) - Embattled mortgage finance company  Fannie Mae &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=FNM.N target=/stocks/quickinfo/fullquote"&gt;FNM.N&lt;/A&gt; agreed to keep billions of dollars more in  cash on hand while it corrects accounting problems, its  government regulator said on Monday.