gpio: mpc8xxx: select GPIOLIB_IRQCHIP

gpio: mpc8xxx: select GPIOLIB_IRQCHIP

This driver uses gpiochip_irq_reqres() and gpiochip_irq_relres() which
are only built with GPIOLIB_IRQCHIP=y. Add the missing Kconfig select.

Fixes: 7688a54d5b53 ("gpio: mpc8xxx: Make irq_chip immutable")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202505180309.1nosQMkI-lkp@intel.com/
Acked-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20250519-gpio-irq-kconfig-fixes-v1-2-fe6ba1c6116d@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>