As done by esden for the F4, remove typedefs and add prefixes to clock enums
This extends this to all stm32 families.
Let's not hide the fact that these variables are structs/enums.
We are filling up the namespace badly enough, we should be prefixing as
much as we can with the module names at least. As users we already run
often enough in namespace colisions we don't have to make it worse.
* CLOCK_3V3_xxx enums renamed to RCC_CLOCK_3V3_xxx
* clock enums (PLL, HSI, HSE ...) prefixed with RCC_
* scale enum of pwr module prefixed with PWR_
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