[PATCH rtems v3 0/7] Add imxrt BSP

[Christian Mauderer]

Hello,

again an updated version. There haven't been relevant changes beneath
patch 3 (some follow up ones in 7) so I'm only sending patch 3.

Changes:

- renames like suggested by Sebastian
- the MPU is now disabled, set up and re-enabled
- every MPU region is only set up once due to that
- I moved the constants for STM32H7 into a separate file to enable the
  main advantage of that initialization: Allowing the user to provide
  a different configuration in his application.

Best regards

Christian