drivers: rtc: stm32: don't enable LL full driver module

The RTC driver does not use any of the functions implemented in the LL full
driver module (`stm32XXxx_ll_rtc.c`), only those provided by the LL header
(`stm32XXxx_ll_rtc.h`).

Disable compilation of the unnecessary full driver module.

Signed-off-by: Mathieu Choplain <[email protected]>

Author: mathieuchopstm

drivers/rtc/Kconfig.stm32

@@ -5,6 +5,5 @@ config RTC_STM32
 	bool "STM32 RTC driver"
 	default y if !COUNTER
 	depends on DT_HAS_ST_STM32_RTC_ENABLED && !SOC_SERIES_STM32F1X
-	select USE_STM32_LL_RTC
 	help
 	  Build RTC driver for STM32 SoCs, excluding STM32F1 series.