pinctrl: intel: Drop unused irqchip member in struct intel_pinctrl

There is no users of irqchip member in struct intel_pinctrl. Drop it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>