General Mills to Sell Stake in Cereals  LOS ANGELES (Reuters) - General Mills Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GIS.N target=/stocks/quickinfo/fullquote"&gt;GIS.N&lt;/A&gt; on  Monday said it will sell an \$835 million stake in its cereal  business to an affiliate of Lehman Brothers Holding Inc.  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=LEH.N target=/stocks/quickinfo/fullquote"&gt;LEH.N&lt;/A&gt; and use the money to buy back 16.5 million of its  common shares from Diageo Plc &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=DGE.L target=/stocks/quickinfo/fullquote"&gt;DGE.L&lt;/A&gt;.