cmsis_6: Integrate with zephyr build system

ARM has deprecated 5.9.0 and we will need to start using CMSIS_6
to get upstream features and continue supporting tf-m.
This commit will integrate it just like CMSIS_5.

Signed-off-by: Robin Kastberg <robin.kastberg@iar.com>
Signed-off-by: Sudan Landge <sudan.landge@arm.com>