hal: spk_prot: Update lock for v-validation and timestamp calculation

Ensure take adev lock before v-validation thread calls spkr_calibrate,
since spkr_calibrate() caller expected to take it. Update
timestamp calculation for nsec for v-validation based on
added value.

Change-Id: I1b4004eb1e809219e36b9c3f733a9b484cf1e8a4