soc: xtensa: intel_adsp: restore bootctl with per-core state

When exiting PM_STATE_SOFT_OFF, the primary core state is always
used to restore bootctl register and the clock and power gating
settings.

This can lead to problems if non-primary core is powered up and down
many times before primary core 0 is powered down the first time.
The saved state in core_desc[0].bctl will be null, and as a result-
power gating and clock gating is not disabled correctly for
non-primary cores.

Link: https://github.com/thesofproject/sof/issues/8642


Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>