Build: Change NS log from interface to test log system

The NS binary in tf-m-tests repo should use its own log
implementations.
This part is missed on the new build system.

This patch fixes this by:
1. Add the tfm NS library into build (the library CMake is added
   by the test repo)
2. Remove the build of log under interface for NS API

Change-Id: Ib25758950700e819863d278f4a97dcae70bedaa1
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
3 files changed