Build: Export configs and files for FF tests

Change-Id: Icfbabc0fb920d9bc18505e2bb4fdfa89541849f5
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/cmake/install.cmake b/cmake/install.cmake
index 6063e1c..cd3d808 100644
--- a/cmake/install.cmake
+++ b/cmake/install.cmake
@@ -26,6 +26,9 @@
 install(FILES       ${CMAKE_BINARY_DIR}/generated/interface/include/psa_manifest/sid.h
         DESTINATION ${INSTALL_INTERFACE_INC_DIR}/psa_manifest)
 
+install(FILES       ${CMAKE_BINARY_DIR}/generated/interface/include/config_impl.h
+        DESTINATION ${INSTALL_INTERFACE_INC_DIR})
+
 install(FILES       ${INTERFACE_INC_DIR}/tfm_veneers.h
                     ${INTERFACE_INC_DIR}/tfm_ns_interface.h
         DESTINATION ${INSTALL_INTERFACE_INC_DIR})