refactor(amu)!: privatize unused AMU APIs

This change reduces the exposed surface area of the AMU API in order to
simplify the refactoring work in following patches. The functions and
definitions privatized by this change are not used by other parts of the
code-base today.

BREAKING CHANGE: The public AMU API has been reduced to enablement only
to facilitate refactoring work. These APIs were not previously used.

Change-Id: Ibf6174fb5b3949de3c4ba6847cce47d82a6bd08c
Signed-off-by: Chris Kay <chris.kay@arm.com>
4 files changed