rtc: stm32: remove dedicated wakeup management

rtc: stm32: remove dedicated wakeup management

There is no more needs to use a dedicated wake up interrupt for RTC as
EXTI block manages by itself now all interrupt lines.

Dedicated wakeup interrupt has been introduced with STM32 MP1 support
commit b72252b6580c ("rtc: stm32: add stm32mp1 rtc support") because GIC &
EXTI interrupts were not yet linked in EXTI driver.

Removing this interrupt won't break compatibility with device trees which
do use two interrupts entries: it could only prevent wakeup from low power
modes on STM32MP1x, but platform power management is not yet available.

Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20230531122732.1515594-1-amelie.delaunay@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>