Build: Set PSA_ARCH_TEST_VERSION for 1.2 RC1

Change-Id: Ic1d83881189cfcfa18a86acf361b838acb536b12
Signed-off-by: Raef Coles <raef.coles@arm.com>
diff --git a/config/config_default.cmake b/config/config_default.cmake
index 0d1ad32..dc7ab25 100644
--- a/config/config_default.cmake
+++ b/config/config_default.cmake
@@ -148,4 +148,4 @@
 set(MCUBOOT_VERSION                     "1.7.0-rc1" CACHE STRING    "The version of MCUboot to use")
 
 set(PSA_ARCH_TESTS_PATH                 "DOWNLOAD"  CACHE PATH      "Path to PSA arch tests (or DOWNLOAD to fetch automatically")
-set(PSA_ARCH_TESTS_VERSION              "master"    CACHE STRING    "The version of PSA arch tests to use")
+set(PSA_ARCH_TESTS_VERSION              "5c0399f2"  CACHE STRING    "The version of PSA arch tests to use")