pinctrl: qcom: spmi-gpio: Make irqchip immutable

The irqchip implementation used inside the gpiochips are not supposed to
be changed during runtime. So let's make the one inside the spmi-gpio
gpiochip immutable.

This fixes the below warning during boot:
gpio gpiochip0: (c440000.spmi:pmic@0:gpio@c000): not an immutable chip, please consider fixing it!

Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20220830092232.168561-1-manivannan.sadhasivam@linaro.org


[switched two lines as indicated by Johan]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>