Revert "soc: intel_adsp/ace: fix CPU halting"

This reverts commit 81908cd3.

This commit introduced a regression on SOF. Value of soc_cpus_active is
set by the core X it self in functions pm_state_set and
pm_state_exit_post_ops. soc_adsp_halt_cpu can by called only by the
primary core.

Signed-off-by: Tomasz Leman <tomasz.m.leman@intel.com>