Change SYSCLK on stm32l4 at runtime

[jorbo]

I'm researching the possibility of porting some existing code into a zephyr environment. The platform is a low power system so we use the MSI clock at a lower frequency as the Sysclk. One thing that is done quite a bit in the code base is switching the SYSCLK from the MSI clock to the PLL to function as a sort of "boost mode". I know that this is possible to do with the stm32 libraries provided by ST but I don't see a way to achieve the same function with the provider zephyr drivers. Is there something I'm missing or is this not something zephyr can do at this point in time?