drivers: clock_control: stm32h7: Use dts based configuration macros
drivers: clock_control: stm32h7: Use dts based configuration macros

Update stm32h7 clock_control driver to make use of macros allowing
dts based configuration in coexistance with existing Kconfig method.

Note: Use of IS_ENABLED is removed as it generates warnings in
checkpatch. This checkpatch behavior needs to be reviewed but may
first require a little clean up of IS_ENABLED macro.

Signed-off-by: Erwan Gouriou <de4d967452b83bb0e37525652734e7d9163b6a4c@linaro.org>

finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr