Add clock config for the 25MHz crystal found on the discovery board.
Verified to work on the STM32F7-Disco.
Reviewed-by: Karl Palsson <karlp@tweak.net.au>
Modified namespaces and types->structs to avoid namespace pollution as
was fixed for other families in:
3a7cbec7: stm32l/stm32f: name space standardization [BREAKING]
