stm32f4: Clean references to stm32f4 specific clock control

Following activation of stm32 common clock driver for stm32f4 series
remove references to stm32f4 specific driver.

Change-Id: I372a0ea046007bcb34944d6b2b8880077583b1d3
Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>
22 files changed