Switch to use CMSIS 6 as default

Change-Id: I019a618e22a66fb39a5b6c993ea6721541b2ba90
Signed-off-by: Jonny Svärd <jonny.svaerd@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 75ffc97..b4fbd9c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,7 +25,7 @@
 # Define build options
 #
 
-SET(CMSIS_VER "5" CACHE STRING "CMSIS Version")
+set(CMSIS_VER "6" CACHE STRING "CMSIS Version")
 
 # Setup paths
 if (${CMSIS_VER} EQUAL 5)