pinctrl: stm32: Manage irq affinity settings

Trying to set the affinity of the interrupts associated to stm32
pinctrl results in a write error.

Fill struct irq_chip::irq_set_affinity to use the default helper
function.

Signed-off-by: Cheick Traore <cheick.traore@foss.st.com>
Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Link: https://lore.kernel.org/20250610143042.295376-3-antonio.borneo@foss.st.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>