drivers: interrupt_controller: add stm32mp2 exti

Add the mp2 exti2 dts to the dtsi file.
Add mp2 exti hal and ll function calls with EXTI2 instance. We use the
EXTI2 instance because it contains the GPIO interrupts in the non-secure
context. (We are trying to build the blinky sample as a first milestone)

Signed-off-by: Youssef Zini <youssef.zini@savoirfairelinux.com>