irqchip/stm32-exti: Add CONFIG_STM32MP_EXTI

To guarantee bisect-ability during the split of stm32-exti in MCU and MPU
code, introduce CONFIG_STM32MP_EXTI.
Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240620083115.204362-2-antonio.borneo@foss.st.com

drivers/irqchip/Kconfig

@@ -404,6 +404,10 @@ config LS_SCFG_MSI
 config PARTITION_PERCPU
 	bool
 
+config STM32MP_EXTI
+	bool
+	select STM32_EXTI
+
 config STM32_EXTI
 	bool
 	select IRQ_DOMAIN