Platform: an521, musca_b1: Add ISOLATION_LEVEL 3 support with IAR build

Signed-off-by: TTornblom <thomas.tornblom@iar.com>
Change-Id: I4e0f46f797d53206fee22c0f1b0e19e45d94997f
diff --git a/toolchain_IARARM.cmake b/toolchain_IARARM.cmake
index de1c369..af65fc7 100644
--- a/toolchain_IARARM.cmake
+++ b/toolchain_IARARM.cmake
@@ -7,6 +7,7 @@
 #-------------------------------------------------------------------------------
 
 cmake_minimum_required(VERSION 3.22)
+cmake_policy(SET CMP0115 NEW)
 
 # Don't load this file if it is specified as a cmake toolchain file
 if(NOT TFM_TOOLCHAIN_FILE)