intel_adsp: ace20_lnl: Fix hang issue on SSP power off

Clearing SPA bit together with OFFLEN bit causes FW hang.
This patch changes sequence to avoid that situation.

Signed-off-by: Jaroslaw Stelter <Jaroslaw.Stelter@intel.com>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>