module_adapter: get the actual period_bytes

[johnylin76]

At present module_adapter, period_bytes is calculated assuming the schedule period is 1ms, which could be arbitrary in practice determined by the topology.

This commit replaces the present calculation by audio_stream_period_bytes(). In addition, the timing for getting period_bytes is moved to the beginning of prepare() (prior to the module prepare). At that moment it is guaranteed that all parameters in components/buffers are settled through the pipeline.