pinctrl: ocelot: Fix interrupt parsing

pinctrl: ocelot: Fix interrupt parsing

In the blamed commit, it removes the duplicate of_node assignment in the
driver. But the driver uses this before calling into of_gpio_dev_init to
determine if it needs to assign an IRQ chip to the GPIO. The fixes
consists in using the platform_get_irq_optional

Fixes: 8a8d6bbe1d3bc7 ("pinctrl: Get rid of duplicate of_node assignment in the drivers")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20220304144432.3397621-3-horatiu.vultur@microchip.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>