drivers: watchdog: stm32MP1 window watchdog during debug

This commit is controlling the WWDG during the Stop mode in debug.
WWDG1 is frozen while the core is in Debug mode, setting the bit
of the DBGMCU APB1 peripheral freeze register (DBGMCU_APB1FZ2)
for the stm32MP1 soc devices.

Signed-off-by: Francois Ramu <francois.ramu@st.com>