klippy: Introduce load_config_prefix() for modules that take parameters

Use both load_config() and load_config_prefix() functions when
dynamically loading a module from the extras directory - if the config
section name has parameters in it then use load_config_prefix().

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/extras/fan.py

@@ -34,6 +34,4 @@ class PrinterFan:
         self.last_fan_value = value
 
 def load_config(config):
-    if config.get_name() != 'fan':
-        raise config.error("Invalid print cooling fan config name")
     return PrinterFan(config)