drivers/clock_control: stm32: Configure CLOCK_STM32_HSE_CLOCK using dt

Kconfig symbol is used in hal_stm32 module to define Cube HAL
symbol HSE_VALUE (cf hal_stm32/stm32cube/CMakeLists.txt).
Due to this specific usage, this symbol should be kept. As a
consequence it could not be replaced by dts equivalent but we can
use dts to configure it.

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