drivers: clock_control: fix IN_RANGE() use in stm32 clock drivers

IN_RANGE() macro from zephyr/sys/util.h returns a boolean value
so it should be treated as such and not compared to a decimal value.
Fix stm32 clock drivers accordingly and simplify places where the
value is compared to true.

No functional change.

Signed-off-by: Etienne Carriere <etienne.carriere@st.com>