Revert "arm: mm: Add export symbol for set_memory_* functions"

This reverts commit f5d256c8c587f53b7e56e355ff952e12872d6ed8.
Revert "arm: mm: Define set_memory_* functions for ARM"

This reverts commit faf265f2a04b92ccf6ea96c7f73acbbef4c25815.