genirq/irq_sim: Order headers alphabetically

For better readability and maintenance keep headers in alphabetical
order.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240122124243.44002-4-brgl@bgdev.pl