Input: force feedback - fix function name in comment

Function name is input_ff_destroy() and not input_ff_free()
Signed-off-by: Roger Quadros <roger.quadros@nokia.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/ff-core.c

@@ -353,7 +353,7 @@ int input_ff_create(struct input_dev *dev, int max_effects)
 EXPORT_SYMBOL_GPL(input_ff_create);
 
 /**
- * input_ff_free() - frees force feedback portion of input device
+ * input_ff_destroy() - frees force feedback portion of input device
  * @dev: input device supporting force feedback
  *
  * This function is only needed in error path as input core will