gpio: altera: Drop .mapped_irq from driver data

struct altera_gpio_chip::mapped_irq is only used in the driver's probe
function. So it's enough if mapped_irq is a local variable, and can be
dropped from driver data.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20250109090802.3763275-2-u.kleine-koenig@baylibre.com


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>