drivers: intc: stm32: add break to switch-clause

add an unconditional break to switch-clause's default case, complying
with required [misra-c2012-16.3] rule which states; An unconditional
break statement terminate every switch-clause.

Found as a coding guideline violation (Rule 16.3) by static code
scanning tool.

Note: Tested on STM32L5 Nucleo-144 board (stm32l552xx).

Signed-off-by: ferar alashkar <[email protected]>

drivers/interrupt_controller/intc_exti_stm32.c

@@ -158,6 +158,7 @@ void stm32_exti_trigger(int line, int trigger)
 		break;
 	default:
 		__ASSERT_NO_MSG(trigger);
+		break;
 	}
 	z_stm32_hsem_unlock(CFG_HW_EXTI_SEMID);
 }