This commit uses the new .. zephyr:code-sample-category directive to
categorize code samples across the tree.
Updates existing legacy references to manually defined targets to now
use :zephyr:code-sample-category: role instead.
Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>
smp and mpu are architecture specific samples and do not apply to
majority of support platforms, so move them to arch/.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
