Restore file_create

file_create shouldn't have the 'filename' argument, because that
defeats the purpose of function 'file_format_filename'.  The code
change was committed by accident.  Related to rapid7#1934.

Author: wchen-r7

lib/msf/core/exploit/fileformat.rb

@@ -30,8 +30,8 @@ def file_format_filename
 		datastore['FILENAME']
 	end
 
-	def file_create(data, filename = nil)
-		fname = filename || file_format_filename
+	def file_create(data)
+		fname = file_format_filename
 		ltype = "exploit.fileformat.#{self.shortname}"
 		full_path = store_local(ltype, nil, data, fname)
 		print_good "#{fname} stored at #{full_path}"