Gives number of the Extended Interrupts and Event Controller (EXTI)
interrupt line connected to the RTC Alarm event.
Used on all series, except WBAX & U5X, where RTC Alarm interrupt is
routed directly to Nested Vectored Interrupt Controller (NVIC) and to
Power Control (PWR) wake-up pins.
Signed-off-by: Abderrahmane Jarmouni <abderrahmane.jarmouni-ext@st.com>
