soc: stm32: stmw32wba: Get stop mode compatible with BLE

Supporting Stop1 mode while BLE RF is enabled requires some specific
adaptation and usage of STM32WBA Cube BLE controller scm API.

scm (Secure clock manager) is in charge of switching clock depending
on RF status and should be informed of PM stop modes scheduling.

Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>