Build: Move 'secure_fw' out of 'app' build territory

'secure_fw' should be a standalone project instead of
being launched by 'app' build. Move it out of 'app'
territory and correct veneer lib settings for 'app'.

Change-Id: Ic50b0df234cbee0741ff9385a0c59ef87070df41
Signed-off-by: Ken Liu <ken.liu@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1b6d722..4dd21e6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 #-------------------------------------------------------------------------------
-# Copyright (c) 2017, Arm Limited. All rights reserved.
+# Copyright (c) 2017-2019, Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -10,6 +10,7 @@
 list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 include("Common/BuildSys")
 
+add_subdirectory(secure_fw)
 add_subdirectory(app)
 add_subdirectory(bl2/ext/mcuboot)