Remove :format default for Gregorian#formats

`:format` is not a valid `type` anyway, so it would never match anyway.

In the `ldml.dtd`:

* For `dateFormatLength`, `timeFormatLength` the `type` attribute is `#REQUIRED`.
* For `dateTimeFormatLength`, `type` attribute is `#IMPLIED`

There are no instances in the code where any of these are missing the `type` attribute.
So while in the future it could technically happen for `dateTimeFormatLength`,
I'd rather the code fail in that case, then silently pass with a nonsense value.

lib/cldr/export/data/calendars/gregorian.rb

@@ -62,14 +62,14 @@ def elements(node, kind, context, width, options = {})
               end
             end
           end
-        
+
           def xpath_to_key(xpath, kind, context, width)
             kind    = (xpath =~ %r(/([^\/]*)Width) && $1) || kind
             context = (xpath =~ %r(Context\[@type='([^\/]*)'\]) && $1) || context
             width   = (xpath =~ %r(Width\[@type='([^\/]*)'\]) && $1) || width
             :"calendars.gregorian.#{kind}s.#{context}.#{width}"
           end
-        
+
           def xpath_width
           end
 
@@ -114,7 +114,7 @@ def extract(path, lambdas)
 
           def formats(type)
             formats = select(calendar, "#{type}Formats/#{type}FormatLength").inject({}) do |result, node|
-              key = node.attribute('type').value.to_sym rescue :format
+              key = node.attribute('type').value.to_sym
               result[key] = pattern(node, type)
               result
             end
@@ -162,4 +162,4 @@ def fields
       end
     end
   end
-end
+end