drivers/clock_controller: stm32: Prepare for dts based configuration

To allow transition to device tree based clock configuration on
stm32 targets, rework clock_control driver to use intermediate
STM32_ macros initially defined as the equivalent Kconfig macros
for now.
Propagate the change in all code using these macros.

The reason to introduce these new macros instead of configuring
Kconfig flags using dt kconfigfunctions is that we'll need
to be able to inform users that Kconfig flags are deprecated
once the whole family conversion is done, to encourage
out of tree users to adopt this new configuration scheme.

Note: For now STM32H7 series and code is excluded.
This is the same for some series specific code such as
PLL mul/div for L0/L1 and XTRE prescaler on F1 series.

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>

drivers/bluetooth/hci/ipm_stm32wb.c

@@ -371,7 +371,7 @@ static void start_ble_rf(void)
 		LL_RCC_ReleaseBackupDomainReset();
 	}
 
-#ifdef CONFIG_CLOCK_STM32_LSE
+#if STM32_LSE_CLOCK
 	/* Select LSE clock */
 	LL_RCC_LSE_Enable();
 	while (!LL_RCC_LSE_IsReady()) {