pinctrl: lynxpoint: Enable pin configuration setting for GPIO chip

It appears that pin configuration for GPIO chip hasn't been enabled yet
due to absence of ->set_config() callback.

Enable it here for Intel Lynxpoint PCH.

Depends-on: 2956b5d9

 ("pinctrl / gpio: Introduce .set_config() callback for GPIO chips")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>