Merged in raiden00/nuttx (pull request #579)

Master

* stm32_hritm: add interface to get timer clock frequency

    stm32_hrtim: fix timer freq calculation

    stm32_hrtim: add compar/capture registers significant bits checking

    stm32_hrtim: minor changes

* stm32f334-disco: add buck converter and boost converter logic

Approved-by: Gregory Nutt <gnutt@nuttx.org>