Build: Export recommended tf-m-tests version

Parse recommended tf-m-tests version from version.txt and export it to
NS build.
tf-m-tests can read this version to check compatiablity.

Change-Id: Ibd3d6dab3d53a774d0f14aaa9dc2f97e467dc728
Signed-off-by: David Hu <david.hu@arm.com>
diff --git a/cmake/install.cmake b/cmake/install.cmake
index 49f293b..699a124 100644
--- a/cmake/install.cmake
+++ b/cmake/install.cmake
@@ -211,6 +211,10 @@
                     ${CMAKE_SOURCE_DIR}/config/cp_check.cmake
         DESTINATION ${INSTALL_CONFIG_DIR})
 
+################### Read recommended tf-m-tests version ########################
+
+include(${CMAKE_SOURCE_DIR}/lib/ext/tf-m-tests/read_version.cmake)
+
 ###################### Install NS platform sources #############################
 
 install(CODE "MESSAGE(\"----- Installing platform NS -----\")")