Add test for z_early_boot_rand32_get() API.
This also improves the coverage for kernel/init.c
Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@intel.com>
This test validates random number generator APIs that
is not related to kernel and should not be part of
kernel tests.
Signed-off-by: Praful Swarnakar <praful.swarnakar@intel.com>