platform: Added deprecation warnings for AN539

This patch modifies the cmake configuration
for AN539 to display the deprecation warning at build-time.

It also adds a LOG_MESSAGE entry on the spm_hal which
displays a run-time notification.

The Deprecated Platforms section of the documentation is
updated to reflect this status change.

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
Change-Id: I1cddb70427ec314562197bca65aeb15172418c39
3 files changed