include/dt-bindings/clock: stm32: Factorize Clock source binding accessors

Rename and factorize clock source bindings accessors by moving them
in common header file stm32_clock_control and remove them from
include/dt-bindings/clock/stm32XY_clock.h files

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