Build: Align with tf-m-tests app build change

Specify tfm_api_ns/platform_ns target sources and includes.
Only add common files and files exported by TF-M secure build.
Leave others to NS builds.

Other minor changes to align with tf-m-tests app_broker build change.

Change-Id: I50056339494f626d22e000af0407055273fc4ad5
Signed-off-by: David Hu <david.hu@arm.com>
3 files changed