test(tftf): prevent secure region access from nwd

This change adds a TFTF test attempting an access to a memory region
marked Secure in the GPT. It is expected this results in a GPF data
abort being caught on the PE.

Signed-off-by: Nabil Kahlouche <nabil.kahlouche@arm.com>
Change-Id: I016775e6a8ba7b398c5770c0a296c09898ebd706
3 files changed