Period size in the pulse audio plugin for QAudioInput is not set correctly

In the pulse audio plugin for QAudioInput, period size is 20 ms converted to bytes for the current format. Period size should correspond to how much a period takes up in pulse audio in order to have any value in working with latency.

Possible candidate for period size is the pa_buffer_attr::fragsize value, obtainable from pa_stream_get_buffer_attr().