General Mills Profit Drops as Costs Rise  CHICAGO (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 Tuesday  reported a steeper fall in quarterly earnings than Wall Street  had expected due to higher costs of key food ingredients and  promotional spending.