Test: Fix build issue with test_suite_sfn_s

The library tfm_test_suite_sfn_s should be created with
architecture configuration of the secure side.

Signed-off-by: Sherry Zhang <sherry.zhang2@arm.com>
Change-Id: I5992a3f127e0c91e30522baa49cc8387bcdf2132
diff --git a/test/secure_fw/secure_tests.cmake b/test/secure_fw/secure_tests.cmake
index 64cf607..74fadfb 100644
--- a/test/secure_fw/secure_tests.cmake
+++ b/test/secure_fw/secure_tests.cmake
@@ -88,6 +88,9 @@
 if (TEST_S_IPC)
     add_library(tfm_test_suite_ipc_s STATIC EXCLUDE_FROM_ALL)
 endif()
+if (TEST_S_SFN_BACKEND)
+    add_library(tfm_test_suite_sfn_s STATIC EXCLUDE_FROM_ALL)
+endif()
 if (TEST_S_FWU)
     add_library(tfm_test_suite_fwu_s STATIC EXCLUDE_FROM_ALL)
 endif()
diff --git a/test/secure_fw/suites/spm/sfn/CMakeLists.txt b/test/secure_fw/suites/spm/sfn/CMakeLists.txt
index 186f038..78de25c 100644
--- a/test/secure_fw/suites/spm/sfn/CMakeLists.txt
+++ b/test/secure_fw/suites/spm/sfn/CMakeLists.txt
@@ -48,8 +48,6 @@
 ########################### Secure #############################################
 
 if (TEST_S_SFN_BACKEND)
-    add_library(tfm_test_suite_sfn_s STATIC EXCLUDE_FROM_ALL)
-
     target_sources(tfm_test_suite_sfn_s
         PRIVATE
             secure/sfn_backend_s_testsuite.c