uart: stm32: add support for STM32F4

Change the clock accessors to a tuple of bus ID of the subsystem and enable
bits for the device - it is clearer to read than the opaque pointers.

Change-Id: I9ae73c222c04adac4cf2bc06e97f4ec199bdac3c
Signed-off-by: Ricardo Salveti <ricardo.salveti@linaro.org>
Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>
3 files changed