Revert "gpio: pxa: Make irq_chip immutable"

Revert "gpio: pxa: Make irq_chip immutable"

This reverts commit 20117cf426b6 ("gpio: pxa: Make irq_chip immutableas")
as it caused a regression on samsung coreprimevelte and we've not been
able to fix it so far.

Cc: stable@vger.kernel.org # v6.16
Fixes: 20117cf426b6 ("gpio: pxa: Make irq_chip immutableas")
Reported-by: Duje Mihanović <duje@dujemihanovic.xyz>
Closes: https://lore.kernel.org/all/3367665.aeNJFYEL58@radijator/
Tested-by: Duje Mihanović <duje@dujemihanovic.xyz>
Link: https://lore.kernel.org/r/20250801071858.7554-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>