arm64: Kconfig: Allow build irq-stm32mp-exti driver as module

Drop auto-selecting the driver, so it can be built either as a
module or built-in.

Signed-off-by: Antonio Borneo <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: AntonioBorneo

arch/arm64/Kconfig.platforms

@@ -309,7 +309,6 @@ config ARCH_STM32
 	select GPIOLIB
 	select PINCTRL
 	select PINCTRL_STM32MP257
-	select STM32MP_EXTI
 	select ARM_SMC_MBOX
 	select ARM_SCMI_PROTOCOL
 	select COMMON_CLK_SCMI