irqchip/stm32mp-exti: Allow building as module

Allow to build the driver as a module by adding the necessarily hooks in
Kconfig and in the driver's code.

Since all the probe dependencies linked to this driver have already been
fixed, remove the not longer relevant 'arch_initcall'.
Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240620083115.204362-7-antonio.borneo@foss.st.com

drivers/irqchip/Kconfig

@@ -405,9 +405,13 @@ config PARTITION_PERCPU
 	bool
 
 config STM32MP_EXTI
-	bool
-	select IRQ_DOMAIN
+	tristate "STM32MP extended interrupts and event controller"
+	depends on (ARCH_STM32 && !ARM_SINGLE_ARMV7M) || COMPILE_TEST
+	default y
+	select IRQ_DOMAIN_HIERARCHY
 	select GENERIC_IRQ_CHIP
+	help
+	  Support STM32MP EXTI (extended interrupts and event) controller.
 
 config STM32_EXTI
 	bool

drivers/irqchip/irq-stm32mp-exti.c

@@ -722,15 +722,8 @@ static struct platform_driver stm32mp_exti_driver = {
 	},
 };
 
-static int __init stm32mp_exti_arch_init(void)
-{
-	return platform_driver_register(&stm32mp_exti_driver);
-}
-
-static void __exit stm32mp_exti_arch_exit(void)
-{
-	return platform_driver_unregister(&stm32mp_exti_driver);
-}
+module_platform_driver(stm32mp_exti_driver);
 
-arch_initcall(stm32mp_exti_arch_init);
-module_exit(stm32mp_exti_arch_exit);
+MODULE_AUTHOR("Maxime Coquelin <mcoquelin.stm32@gmail.com>");
+MODULE_DESCRIPTION("STM32MP EXTI driver");
+MODULE_LICENSE("GPL");