Enhance low-level API of libmm (Memory Protection & Caches)

by Hesham Moustafa AL-matary for RTEMS Project

The current code of MMU support is not mature enough. It’s important to have a reliable high-performance easy-to-port, low-level MMU infrastructure for RTEMS (as being RTOS) and that’s what the project is partially about. Also libmm (memory management library) should include cache manager and give a clear picture of how MMU/Caching interact not only for uniprocessors, but also for multiple processors systems.